H. M. Kasper

Room‐Temperature Electrical Properties of Ten I‐III‐VI2 Semiconductors

The room‐temperature electrical properties of ten I‐III‐VI2 (I=Cu, Ag; III=Al, Ga, In; VI=S, Se) compounds are presented. The resistivities of eight of these compounds are rapidly changed by annealing under maximum and minimum chalcogen pressures. The Cu compounds can readily be made p type, a feature lacking in the analogous II‐VI compounds. However, the Cu compounds with energy gaps of 1.7 eV or above have not been made n type.

CuInSe2/CdS heterojunction photovoltaic detectors

We report CuInSe2/CdS p‐n heterojunction photovoltaic detectors which display uniform quantum efficiencies of up to ∼70% between 0.55 and 1.25 μ. Response times as short as 5 nsec have been observed. A weak electroluminescence (0.01% external quantum efficiency) peaking near 1.4 μ has also been observed at room temperature.

Efficient CuInSe2/CdS solar cells

We report the preparation of a CuInSe2/CdS heterojunction solar cell having a solar power conversion efficiency of 12% measured on a clear day in New Jersey (∼92‐mW/cm2 solar intensity).

Analysis of the electrical and luminescent properties of CuInSe2

We discuss the electrical properties and the luminescence spectra of CuInSe2 melt−grown single crystals as a function of the growth and annealing conditions, and the presence of extrinsic dopants such as Zn or Cd. We find that crystals grown from melts containing a slight Se excess or annealed under maximum Se pressure are p type, whereas crystals grown from excess In melts or annealed under minimum Se pressure (vacuum) are n type. The low−temperature photoluminescence spectra of crystals as−grown or annealed between 400 and 700 °C are characteristic of the conductivity type. At 77 °K, p−type crystals emit in a band peaked at 1.00 eV (type A spectrum), whereas the emission of n−type crystals peaks at 0.93 eV (type B spectrum). Types A and B spectra can be interchanged by alternate anneals in minimum or maximum Se pressure. Type B emission dominates the electroluminescence spectrum of p−n junctions. A sharp band−to−band emission at 1.04 eV is present in the 77 °K photoluminescence spectrum of some high−res...

Debye temperature and standard entropies and enthalpies of compound semiconductors of the type I-III-VI2

The heat capacities at constant pressure have been measured for CuInSe2, CuInTe2 and AgGaTe2 in the temperature range 1K ≤T≤40K and for CuInS2 and AgInTe2 between 1 K and room temperature. From the low temperature data we derive the following Debye temperatures θD in the limit T → O K: θD(CuInS2) = 273 K, θD(CuInSe2) = 222 K, θD(CuInTe2) = 191 K, θD(AgGaTe2) = 182 K and θD(AgInTe2) = 156 K. A plot of the average atomic heat capacity at constant volume Cv shows that the data scale to one general curve for all 5 compounds considered in this paper. This is, also, true for a plot Cv, i.e., all I-III-VI2 compounds measured thus far deviate similarly from the Debye approximation. By integration of the general curves Cv(T/θD) and θD x Cv(T/θD) we derive tne standard entropies S0298 and energies E0298-E00 of 11 compounds of the type I-III-VI2, for which the Debye temperatures are known. The difference between the energies E0298-E00 and enthalpies H0298-H00 is within the error limits of the experimental data (< 1%). The molar S0298 and H0298-H00 values for the I-III-VI2 compounds are approximately twice the corresponding molar values for their II-VI isoelectronic analogs. The thermodynamic functions at standard state obtained by integration of the experimental data are all < 10% smaller than the corresponding values estimated on the basis of the Debye approximation.

Linear and nonlinear optical properties of LiInS2

LiInS2 is an AIBIIIC2VI ternary semiconductor crystallizing with mm2 symmetry. The useful transparency range is 0.5–8 μ, over which we have measured the refractive indices. The optical nonlinear coefficients for second harmonic generation have also been measured. The nonlinear figure of merit is comparable to that of AgGaS2. Three‐frequency collinear phase matching is possible in LiInS2 and is analyzed in some detail. LiInS2 is judged to be a potentially more useful optical nonlinear material than the analogous compound LiGaO2.

Green electroluminescence from CdS–CuGaS2 heterodiodes

Heterodiodes have been prepared by vapor‐deposition expitaxy of n‐type CdS on p‐type CuGaS2. Typical diodes emit green light under forward bias with external quantum efficiencies of 0.1% at 77 °K and 0.001% at room temperature. The radiative recombination results from electron injection into the CuGaS2.

Junction electroluminescence in CuInSe2

We report the first observation of homojunction electroluminescence in CuInS2. These homojunctions are made by two different annealing procedures which convert a surface layer of p−type crystals. Diodes made by low−temperature (200 °C) In−Ga diffusion show a rectification ratio of 17000:1 at 2 V and a zero bias resistance of 1×107 Ω. For diodes made by high−temperature (600 °C) annealing in InCl3 the values are 15000:1 and 3×107 Ω, respectively. Electroluminescence has been observed in diodes made by In−Ga diffusion. The spectrum peaks at 1.48 eV at 300 °K and at 1.42 eV at 77 °K. The internal quantum efficiency is 10−5 at 300 °K and 10−3 at 77 °K.

Some properties of AgAl Te 2 , AgGa Te 2 , and AgIn Te 2

The valence-band structure and the semiconducting properties of the

TERNARY PHASE RELATIONS IN THE VICINITY OF CHALCOPYRITE COPPER GALLIUM SULFIDE

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