Spectral responses of the n-PbTe/p-Pb₁₋ₓ SnₓTe heterojunctions

Optica Applicata, Vol. X I I , N o . 2, 1982

Spectral responses of the n-PbTe/p-Pb^Sn^Te

heterojunctions

Waldemar Larkowski, Antoni Rogalski

In stitu te of Technical P hysics, M ilitary A ca d em y of Technology, 0 0 -9 0 8 W a rsaw , Poland.

T h e influences of the Burstein-M oss effect on th e spectral dependence of th e absorption coefficient for P b i^ S n ^ T e and on the spectral characteristics of the w -P b T e /p -P b i.a:Sna.Te heterojunctions h ave been analysed. I t has been poin ted out th at for carrier concen­ tration in P b 1.xSnxT e above 1025 m “ 3 the spectral cu toff of the heteroj unction is de­ term ined b y the P b T e m aterial used. I t has been also a ttem pted to fit the characteris­ tics calculated theoretically for this kind of heteroj unctions w ith those m easured experim entally.

1 . Introduction

The narrow-gap semiconductors Pb^Sn^T e are widely used in the infrared technique. This is the basic material used in production of photodiodes of various structures, among them homojunctions, heterojunctions as well as Schottky junctions. Heterojunctions w-PbTe/p-Pb1.a.SmcTe are produced mainly by liquid phase epitaxy by depositing the P b ^ Sn^Te semiconductor layer of narrower energy gap onto a single crystal substrate of PbTe [1-3] or to deposit successively, first the Pb^Sn^Te layers and then the PbTe [4-8]. Some attempts have been also made to produce the heterojunctions by the hot-wall epitaxy technique [9-13]. In all the cases theheterojunctions are illuminated from the PbTe side, i.e., from the side of semiconductor of wider energy gap. The advantage offered by heterojunction structure is that the radiation of the wavelength outside the PbTe absorption edge is absorbed in Pb^Sn^Te far from photodi­ ode surface. There are no losses caused by surface recombination in the case of thick PbTe region. The application of the semiconductor of greater energy gap on one side of the junction diminishes the value of the saturation current for the non-illuminated photodiode and by the same means increases the dif­ ferential resistance of the diode for polarization equal to zero.

Various spectral responses of photodiodes have been obtained, the spectral cutoff Xc of which was not always determined b y the P b ^ S ^ T e material. In the works [9 ,1 0 ,1 2 ] the spectral responses have been measured, long wave­ length edge of which was determined by PbTe. The Xc shift may be influenced b y : i) The concentration level in Pb1.jBSniBTe as well as the associated Burstein- Moss shiijjb and the carrier life-time.

ii) The diffusion process in the PhTe-Pb^Sn^Te interface occurring during the heterostructure production — the influence of this process being essential when the heterostructure is produced at high temperature [8].

206 W . Labkowski, A. Bogalski

In order to interpretate in a convincing way the different types of measured spectral response for w-PbTe/p-Pb1.iCSna.Te the calculations of these characteris­ tics made in the present work for different carrier concentrations in P h ^ n ^ e and different depths of junction were performed by neglecting the influence of the diffusion on PbTe-Pb1.a.SnxTe interface (this topic is discussed in [8]). Also, some attempts were made to fit the theoretically calculated responses to those measured experimentally. Since the knowledge of the dependence of the absorp­ tion coefficient for PbTe and Pb1.xSnxTe upon the wavelength and the carrier concentration is necessary to perform the calculations also this problem was dealt with.

2 . Absorption coefficient

Interband absorption in lead and tin chalcogenides is a more complex pheno­ menon than in semiconductor of parabolic bands. This is caused b y :

i) anisotropic and multi-valley structure of both conduction and valence bands,

ii) non-parabolic energy dispersion.

iii) dependence of matrix elements on momentum operator h.

In papers [14, 15] the interband absorption was discussed in the lead and tin chalcogenides based on six-band Dimmock model and two band Kane modeL A good agreement has been achieved between theoretical calculation results and those obtained in experimental measurements of the spectral dependence of the absorption coefficient for Pb1.iCSna;Te at the vicinity of the absorption edge [15]. However, for photon energy above 1.5 Eg the experimental coefficients of absorption were higher than those calculated theoretically, while the discrep­ ancies were greater for Dimmock model. The dependence of absorption coeffi­ cient upon the composition x and the temperature at the absorption edge vicinity is better described by the Kane model [15].

For lead and tin chalcogenides the absorption coefficient, according to Kane model, has the form [14]

% ) = ( / „ - / „ ) , (1>

nr

where Eg - energy gap, nr - refraction coefficient, f(z) = (1 -f z)1/2 (1 +2z)2/(3V2 z2)y

z = hvjEg, h - Planck constant, v - radiation frequency, f v and f c - Fermi-Dirac

functions for holes and electrons, respectively.

The last term in the expression (1) takes into account band-filling. From the analysis of the absorption band for Pbj.a.Sn^Te of the composition 0 < x < 0,21 within the temperature range 90 < T < 300 K given in [14] the valpe of K

= (6.5 ±1*6)-10s eV-1 cm -1 is reported.

In the case of Boltzmann statistics valid for the nondegenerated semicon­ ductors when the conduction and valence bands are empty, the last term in the

Spectral responses o f the n -P bTeJp-P b1.xSnxT e heterojunctions 207

w

av

el

en

gt

h

(nm)

w

av

el

en

gt

h

(urn)

208 W. Labkowski, a. R OGAX8KI expression (1) is equal to unity. As the band is being populated - which affects essentially the spectral dependence of the absorption coefficient - ( / » —/<.) diminishes, which is the so-called Bur stein-Moss effect. Fig. 1 shows the influ­ ence of the carrier concentration on the absorption coefficient dependence upon the wavelength for PbTe and Pb0 78Sb0>22Te at the temperature of 77 K . The calculations have been based on the expression (1), taking K+ — 6.5 · 105 eY-1cm-1 [14] and nr — 6.5 and 7.2 for PbTe [16], and P b^Sn^T e [17], respectively. The position of Fermi level, necessary to determine (fv —f c), has been calculated in the way described in Appendix. From Fig. 1 it may be noted that, as the con­ centration increases, the absorption band suffers from the spreading being simultaneously shifted toward the shorter wavelength. Besides, for the given carrier concentration the Burstein-Moss shift is of greater influence for semi­ conductors of less energy gap width (of less effective masses) as it is the case for Pb0.78Sn0.22Te.

3 . Spectral responses

In Figure 2 the band structure for a typical heterojunction is presented. The total quantum efficiency is the result of contribution from four regions: two neutral regions of opposite types of conduction and two regions of space charge of widths w1 and w2, respectively. In accordance with this we have

n = Vh+ Vd r+ Vd r+ % 1 (2 )

where and rfoB denote the quantum efficiencies of the space charge regions in the w-type and p-type semiconductors, respectively. The particular compo­ nents of the quantum efficiency have the forms [18]:

° iLh ia1Lh-\-y1- e - a^ [ y 1ch{xnfLh) + sh(xnILh)] _ r ^_aiXn\

yl8h{x j i ^ k ^ ) a' Lh6 } ’ (3)

Vp a2^e 0 — al*Q~a2w2>

a l L l - 1 (4)

x { a 2X6 y 2 \ch [(d - w2) /J 6] - «-«*«-*>] + 8h [(d w2) ILe] + a2Le

y2s h [ (d - w 2)/Le] + ch(d - w2) /Le

)■

*8>b = e ' aii( l - e - w * ) ,

(5)

(6 )

where ax and a2 — absorption coefficients in w-type and p-type regions, respec­ tively, yx = 8tLhfDh, y 2 = 82Le/De , Le and Lh — diffusion length for electrons and holes, respectively, Dt and Dh - coefficients of diffusion for electrons and holes, respectively, sx and s2 - surface recombination velocities for illuminated and back photodiode surfaces, respectively.

Spectral responses o f the n -P b T e lp -P b \ ^ S n xTe heterojunctions ₂₀₉ The above formulae do not take account of the losses caused by the reflec­ tion of the radiation on the illuminated surface of the heterojunction. In order to encounter also these losses the expressions should be multiplied by (1 —r). Additionally, the expressions (4) and (6), have been derived by

neglect-F ig. 2. B an d structure of the heterojunction

ing the radiation reflection on the interface surface x = t. This reflection is conditioned by the refractive index difference in the n- and p-type regions. They can be taken into account by replacing the term exp ( — axt) exp ( —a2w2) by a more complex transmission factor given by Mi l n e s and Fe u c h t [19]. Because of the similar values of the refraction coefficient for PbTe and Pb0>8Sn0 2Te the reflection is close to zero and may be neglected.

The charge space widths wx and w2 are determined by the relative doping levels and dielectric constants for semiconductors on both sides of junctions

[18]: « , - r 261 e 2N a -1 1 /2 F 1 1 № s xN 1 Jr s 2N 2 v bi I i № - r 2ei S x N i - l l / 2 T7\ I ‘ L i N . e x N z v bi I i

where Vbi = H q(EFp—EFn) is the diffusion potential (EFn and EFp denote the energy at the Fermi level of isolated semiconductors creating the respective region of n- and p-types of the hetero junction).

The relations (3) and (4) are derived under assumptions that the concen­ trations of excess minority carriers close to the edge of the space charge region are reduced to zero by the electric field in the depletion region. Such an assump­ tion is justified under the condition that the discontinuity of energy in the con­ duction (valency) band AEC(AEV) is small ( < lcT/q) in n Ip (pin) heterojunction [18]. In the opposite case the minority carriers from the region of less energy gap may be impeded during the current flow through the junction, which results consequently in diminishing the photocurrent (for example, an electron moving

210 W. La s k o w sk i, A. Rogalski \ \ \ (sł|un-|3j) AjjAjsuodsaj

w

av

el

en

gt

h

(ł

im

)

Spectral responses o f the n -P b T e /p -P b i.x8 n xTe heterojunctions 211 E 3 (sjjun‘|9J) AjjAisuodsaj _Fig . 3 . C a lc u la t e d s p e c tr a l r e s p o n s e s o f s e n s it iv it y fo r n -P b T e /p -P b 0 .7 8 S n 0 .2 2T e h e t e r o ju n c t io n s a t 7 7 K . D o n o r c o n c e n t r a t io n s i n P b T e -1 0 23 m -3 , a c c e p t o r c o n c e n t r a t io n s P b o .7 8 S n o .2 2 T e is m a r k e d in fi g u r e s : a . t/L ^ = 0 .1 , sx = 0 ; b . t/L ^ = 0 .1 , S j = 1 0 4n /s ; e . t/ L h = ! , « ! = 0 ; d . < /£ * = 1, -1 0 * m /s

212 W. Lar k o w sk i, A. Rogalski

from the region of p-type to the region of w-type is slowed down slightly by

AEC - see Fig. 1). From the work [13] it follows that no energy discontinuity

should be expected in PbTe/Pb0 86Sn0<14Te heterojunctions.

The presence of both the surface states and the defects caused by the mis­ fitting of the lattice and imperfect technological process of heterojunction pro­ duction is an additional factor complicating the discussion. If the effective life-time of carriers inside or close to the space charge is very short, the electrons and holes generated may recombine quickly instead of being separated by the junction. Consequently, the photocurrent will be diminished. In the case of the considered Pb^Sn^Te (x 0.20) heterojunctions the lattice constants are fitted very well (they differ only by 0.3°/o) while their coefficients of linear expansion are identical. From estimations carried out in the work [13] it follows that the interphase recombination rate in PbTe /Pb0 86Sn0 UTe heterojunctions conditioned by the misfitting of the lattice has no influence on the photocurrent value. Additional defects caused by inappropriate technology used in production of heterojunctions may be a source of other factors increasing the recombination rate and diminishing the photocurrents.

F rom 'th e above discussion it follows that the formulae (2)-(6) may be employed for calculation of quantum efficiency of heterojunctions of %-PbTe/p -Pbi^Sn^Te type.

For calculations of spectral characteristics of sensitivity the following for­ mula was used

where X — wavelength, q — electron charge, c — light velocity, 22 — differential resistance of the diode.

When relative units are used the knowledge of 22 becomes unnecessary. The parameters required for calculations are collected in Table. The Fermi level and diffusion coefficients are counted in the way described in the Appendix.

«

T h e param eters assum ed for calculations of spectral sensitivity o f n -P b T e /p -P b 0<78 Sn0.22 T e heterojunctions P b T e P b 0.78Sno.22T e Ejr [m e V ] D [m 2/s ] T [8] {A [m 2/V s ] Ejp [m e V ] D [m 2/s ] T[S] [m 2/V s ] 1022 _{- 2 2 0 .0 1 6 3 1 0 “ 7 2 .5 - 1 5 0 .0 1 9 2 -1 0 ~ 7 3} 3 1 0 22 - 1 4 0.0 17 10“ 7 2 .5 — 7 0.021 1 0 " 7 3 1023 - 6 0.0 1 8 4 -1 0 -® 2 .5 3 0.0 23 1 0 -8 3 3 1 0 2* 3 0.0 22 1 0 ~ 8 2 .5 14 0 .0 3 4 1 0 -9 3 1024 _{16 0.0 32 lO - 8 2.5 32 0.0 44} IQ -io _{2 .5} 3 1 0 24 36 0 .0 5 4 1 0 -9 2 .5 58 0 .0 3 9 3 -1 0 - 11 1.4 1026 _{73 0.0 5 3 1 0 ~ 10 1.4 102 0 .0 2 4 1 0 - 11 0.5 5}

Spectral responses o f the n -P b T e /p -P b i^ .8 n xTe heterojunctions ₂₁₃ The life-times given in Table are determined by the interband recombination of Auger and radiative types [20,21], while the carrier mobility has been accepted after the papers [22, 23].

In Figure 3 the calculated spectral characteristic of n-PbTe/p-Pb0,78Sn0 22Te in the 77 K temperature are shown. The calculations are carried out for two classical design cases of the photodiode (when (t+d)->oo, the influence of the recombination rate becomes inessential) illuminated from the PbTe side, i.e. for the optimal construction when t/L — 0.1 [24] and when t/L = 1. The cases of zero and high (104 m/s) surface recombination rates were studied.

It has been assumed that the donor concentration in PbTe is constant and amounts to 1023 m“ 3 (for such concentration no influence of the Burstein-Moss effect in this material is observed - see Fig. lc), whereas the concentration of acceptors in Pb0#78Sn0 22Te is variable, which is marked in Fig. 3. From this figure it may be seen that the Burstein-Moss effect on the spectral characteristics is distinct at the hole concentration above 1023 m~8 in Pb0 78Sn0 22Te. At the concentration above 102S m“ 3 the long wavelength sensitivity limit of hetero­ junctions is determined by the PbTe region. Such a long shift of l c is caused by two effects: the Burstein-Moss effect and the very low lengths of the carrier diffusion path in P b ^ S n /re . Consequently, minimal part of the carriers generat­ ed in the region of p-type reaches the junction and gives its contribution to the photocurrent. It may be noted that the spectral characteristics of hetero­ junctions in which the junction is positioned deeply are more selective. The surface recombinations lower the photocurrent in the short wavelength range.

wavelength (jjm)

F ig. 4 . The relative sensitivity o f 0-1 p h o to ­

diode at 77 K according to th e paper [1 2] (solid line). T h e broken line is used to m ark the response calculated theoretically and fitte d to it fo r the follow ing pa ram eters:

Nd= 1022m - 3 , Na= 1 .5 · 1025m - 3 , x = 0 .2 ,

xn/L = 0 .0 4 , «1== 5 - 1 0 4 m /s , xn => 2 .5 pm.

Also some attempts have been made to fit the theoretically calculated spectral responses of w-PbTe/p-Pb1.a.SnxTe heterojunctions. For this purpose we have used some experimental data given in the works from which the measur*

214 W . La s k o w sk i, A . Rogalski

ed spectral responses were taken. The values of the diffusion coefficients and the life-times were evaluated by extrapolating the values given in Table. In Fig. 4 the continuous line is used to show the relative sensitivity of the photo­ diode (7-1 according to [12], while the broken line presents the response calculat­ ed theoretically. From the measurements of the G-V characteristics reported in [12] it follows that the concentration of donors in the less dopped region of the junction amounts to about 1022 m-3. Therefore, the above electron concen­ tration in PbTe was accepted in calculations. In order to fit correctly the measur­ ed characteristics in the short wavelength range it was necessary to assume high value of the surface recombination rate sx = 5-104 m/s. The measured characteristics of the B -4 diode at 77 K temperature as reported in [11], as well as the theoretically calculated response best fitted to the previous one, are, in turn, shown in Fig. 5. It should be noted, that the theoretical calculations do not foresee the measured local sensitivity minimum at the 8.5 /zm wavelength.

F ig. 5. T h e relative sensitivity of B-4

photodiode at 77 K according to th e paper [ 11 ] (continuous line). T h e b ro ­ ken line is used to m ark the response calculated theoretically and fitte d to

it for the follow ing param eters:

Nd = 1022 m - 3 , Na = 3 · 1023 m " 3 ,

x = 0 .2 1 , xn/L = 0 .0 5 , sx = 104 m /s ,

xn = 3.2 fim

Formerly, it was noted that in the case of deeply positioned junctions the spectral characteristics are more selective. The shortwavelength edge is determin­

ed by the radiation absorption in the upper energy gap of PbTe, while the .spectral cutoff is due to the Pb^Sn^Te material. Such response measured by the authors in [1] is shown in Fig. 6. The w-PbTe/p-Pb1.a;Sna.Te heterojunctions were illuminated from the PbTe monocrystal side of the thickness ^ 250 /on and the^electron concentration of about 1023 m -3. In order to well fit the longwave- length part of response it should be assumed that the composition of Pb^Sn^Te

Spectral responses o f the n -P b T e /p -P b i.x8 n xTe heterojunctions 215 is 0.22, instead of 0.20 given in [1], and that the concentration in this material is 2-1023 m~3. The surface recombination rate has no influence on the spectral characteristics due to the thick region of PbTe.

The presented results of calculations of spectral responses of the n-PbTe jp -Pbj.JSsTe functions confirm the fact that the spectral cutoff limit depends upon

F ig . 6 . T he relative sensitivity of n -P b T e /p -P b i _ xSnxT e hetero junction according to the paper [ 1]. The broken line is used to m ark the re­ sponse calculated theoretically and fitted to it for the follow ing param e­

te rs: Nd = l O ^ - m - 1, Na = 2 - 1 0 23

m “ 3, x = 0 .2 2 , xn — 2 5 0 pm

the carrier concentration in Pb^Sn^Te. The Xc shift may be influenced also by the diffusion process at the PbTe-Pb1.xSnxTe interface [8]. However, for high carrier concentration in Pb1.xSnxTe the spectral responses may be determined also b y the PbTe semiconductors.

A ppendix

Fermi level and effective masses

T h e calculation of Ferm i level has been carried out basing on th e K a n e m odel, using the

generalized F erm i-D irac integral. In this m ethod the dependence of the Ferm i level EF upon

th e carrier concentration is determ ined b y th e relation [2 5 ]

(Al)

216 W . Lar k o w sk i, A . Rogalski

where / => {exp [(E — EF)/kT] + 1} _1 is th e D ira c-F erm i distribution function, z = E/JcT,

P = IcTjEg, E - energy, Eg - energy g ap , k - B oltzm a n n constant, h - Planck constant,

mfo — d e n sity -o f-sta te effective m ass at the b o tto m of th e band.

On th e basis o f the work [2 6 ] it has been assum ed th at the effective mass anisotropy

coefficient for th e longitudinal toJ and transverse m\ m ass com ponents is equal K — 1 1 ;

to* — 0 .1 4 6 m (Eg/eV), to^> = (toJtoJ2)1/3 = 0.81 to (Eg/eY), for N = 4, where to d e­

notes the free electron m ass.

Coefficient of diffusion

In the state of therm al equilibrium the therm al coefficient of carrier diffusion in th e sem icon­ ductor of « -t y p e is [2 7 ] J>e - ~ / g{E)fc(E)dE «e _»___________ 8 / > «> % dE (A2)

where pe — electron m obility.

B y substituting b oth the state density function according to th e K a n e m odel [2 5 ]

(A 3 )

and the F erm i function f e and assum ing th a t 17 == EpjkT w e obtain

y k T f[z (l+ 2 p z )]ll* ( 1 + 2pz) (&-* + l)~ 1dz

/[«(1 +20s]1/2(l +2pz)ez- i ( e s- ,i + l)~2dz

0

(A 4 )

In th e case o f nondegenerated sem iconductors this expression m ay be reduced to th e Einstein form ula

D u e to th e sy m m e try o f the b an d structure o f lead and tin chalkogenides De ms

R eferences

[ 1] AndrewsA .M ., LongoJ .T ., Clarke J .E ., GertnerE .R ., A p p l. P h y s. L e tt. 26 (1 97 5),

438.

[2] Wang C.C., KalisherM .H ., Tract J .M ., Clarke J .E ., LongoJ .T ., S olid-State E lec ­

tron. 21 (1 97 8), 625.

[3 ] WangC .C ., KimM .E ., J . A p p l. P h y s. 5 0 (1 97 9), 3733.

[4 ] Chia P .S ., Balon J .R ., Lockwood A .H ., Randall D .M ., Renda F .J ., De Vatjx

L .H ., Kimura H ., Infrared P h y s. 1 5 (1 97 5), 2 7 9 .

[5 ] WangC .C ., Hampton S .R ., Solid-State Electron 1 8 (1 975), 121.

[6 ] KosogovO .Y ., Kim Gvap De, Maramzina M .A ., Girich B .G ., Nikolaev M .I ., Pklevin

Spectral responsee o f the п-РЪТеjp -Pbi .x Snx Te heterojunctions 217

[7 ] Stafeev Y .I ., Banin E .S ., Gusarov A .V ., TerehovichT .F ., Pelevin O .V ., Nikolaev

M .I ., F iz. T ekh. P oluprov. 12 (1978), 1714.

[ 8 ] Stafeev V .I ., Banin E .S ., TerehovichT .F ., Mironova O .A ., Pelevin O .Y ., Girich

B .I ., Mohovata T .G ., Nikolaev M .I ., F iz.T ekh .P olu prov. 12 (1 978), 1723.

[9 ] KasaiI ., Basset D .W ., Hornung J ., J .A p p l.P h y s. 47 (1 97 6), 3167.

[1 0 ] Igras E ., RogalskiA ., Electron Technol. 10 (1977), 471.

[ 11] Rogalski A ., Electron Technology, to be published.

[ 12] RogalskiA ., Thin Solid Filins 67 (1980), 179.

[1 3 ] Bittner H., BremserW ., Herrmann K .H ., Proc. 9th Symp. of the IM EKO Technical

Committee on Photon Detectors, Budapest 1980.

[1 4 ] Genzow D ., Herrmann K .H ., Kostial H ., Rechenberg J ., Yunovich E .E ., P h ys.

S ta t. Sol. (b) 86 (1 978), K 2 1 .

[1 5 ] Genzow D „ Mironow A .G ., Ziep 0 . , P h ys. S ta t. Sol. (b) 90 (1 978), 535.

[1 6 ] Zemel J .N ., JensenJ .D ., Schoolar R .B ., P h y s. R ev 1 4 0 (1965), A 3 3 0 .,

[1 7 ] Low ney J .R ., Senturia S .D ., J. A p p l. P h y s. 47 (1976), 1771.

[1 8 ] Hovel H .J ., Semiconductors and Semimentals (edited b y R .K . W illardson and A .C . Beer),

Y o l. 11, A ca d em ic Press, N ew Y o r k ,%San Francisco, London 1975.

[1 9 ] MilnesA .G ., Feucht D . L ., Heterojunctions and Metal-Semiconductor Junctions, A c a ­

dem ic Press, N ew Y o fk and Lon don 1972.

[2 0 ] Ziep O ., Genzow D ., Mocker M ., Herrmann K .H ., P h ys. S tat. Sol. (b) 99, (1980),

129.

[2 1 ] Grudzień M ., RogalskiA ., Infrared P h y s. 21 (1 98 1), 1.

[2 2 ] Ravich Y n . I ., EfimovaA .B ., Tamarchenko Y .I ., P h ys. Sta t. Sol. (b) 45 (1 973), 453.

[2 3 ] S iz o v F .F ., LASBiKAREEV G. V ., Radchenko M .V ., Orletskii V .B ., Gbigorovich

E .T ., F iz. T ek h . Poluprov. 1 0 (1 976), 1801.

[2 4 ] Rogalski A ., Rutkowski J ., Infrared Physics, to be published.

[2 5 ] Kołodziejczak J ., A c ta P h ys. P ol. 2 0 (1961), 28 9.

[2 6 ] Gureev D .M ., Zasavitski I .I ., Natsonashvili B .N ., Shotow A .P ., F iz.T e k h . P oluprov.

12 (1 97 8), 708.

[2 7 ] Smith R .A ., Półprzewodniki, P W N , W a rszaw a 1966 (in P olish).

Received August 18, 1981 Спектральные характеристики гетероструктур п-РЬТе/р-РЬ1.ж8п а. Те Проанализировано влияние эффекта Бурштейна-Мосса на спектральную зависимость коэффи­ циента поглощения РЬх-хБп^Те и на спектральные характеристики гетероструктур л-РЬТе/р-РЬ]^ Бп^Те. Доказано, что при концентрации носителей в РЬ1.х8па;Те выше 1025 м - 3 длинноволновой предел чувствительности гетероструктур определён материалом РЬТе. Предприяты также попытки согласования теоретически рассчитанных характеристик этого типа гетероструктур с экспери­ ментально измеренными.