This paper relates different points concerning defect levels and lattice defects in CulnSe 2 and the I-HI-VI2 compounds. First, we review the main levels observed. Second, we propose a hypothesis concerning the electrical compensation processes acting in the I-III-VI} materials. Third. we discuss the nature of the defects responsible for the levels, and improve interpretations, by carrying out the deformation potential in antisite defects. Especially, these calculations reinforce the idea that the "hydrogenic-type" acceptor observed in the I-IIl-VI2 materials must rather be attributed to the eu or Ag vacancy than to an antisite defect.
The cathodoluminescence of single crystals of CulnSe z obtained by melt-grown and iodine chemical transport was studied. As-grown crystals and crystals annealed in Se, In, or in a vacuum were used. We show the emission intensity decreases when the conductivity changes from n to p and then increases due to the decrease of the number of donors created by Se vacancies. We also show that two donor levels (60 and 80 me V) are introduced by the Se vacancy probably associated with impurities, and that the cation (probably CuI vacancy causes an acceptor level at 40 meV. Another acceptor level is also determined, having a binding energy ~ 80 meV. 1154 J.
Dedicated to Prof. Dr. D r . h. c. D r . E. h. P. GORLICH on the occasion of h i s 80th birthday T h e I-111-V12 compounds, which AgInSZ belongs to, are direct energy gap semiconductors (chalcopyrite structure) which show very interesting electrooptical properties /1, 2/. AgInS2 is unique among these compounds as i t can exist in two crystal forms: chalcopyrite and orthorhombic /3, 4/. The orthorhombic form is stable a t high temperature ( T > 620 OC) and the quadratic form a t low temperature (T < 620 OC). The band structure a t the 'l? point has been given by Shay et al. /5/ according to electroreflectance measurements. Inthis notewe are only interested in the chalcopyrite form, whose energy gap is 1.90 eV a t low temperature and 1.87 eV a t room temperature /5/. AgInS2, annealed in sulphur a t 600 OC for several days, shows a characteristic luminescence spectrum which is investigated in this note.The crystals used are p a r t s of an ingot obtained by slow cooling (2 K/h) of the liquid formed by the stoichiometric mixture of the elements (99. 999% purity) sealed in a quartz tube and heated a t 1000 OC during 4 8 h. We have verified by X-ray analysis that the ingot obtained is formed of chalcopyrite AgInS2. The crystals were then annealed a t 600 OC in the sulphur during 10days.The luminescence w a s excited by a n electron gun with an acceleration voltage of 20 kV. The light was analyzed by means of an Oriel spectrometer followed by a photomultiplier and a PAR box-car integrator. Fig. 1 shows the luminescence spectrum a t liquid He a t various times t after the excitation pulse end. A shift of the emission peak towards low energies is observed when t increases. The weaker emission bands lying on the low energy side of the spectrum and spaced r a t h e r regularly also shift towards low energies. They could be phonon replicas of the main emission. Fig. 2 shows the luminescence spectrum for two different excitation intensities. A shift of the emission peak 1) av. d e Villeneuve, 66025 Perpignan, France.
This article is a study of copper, indium, and gallium interdiffusions in In2Se3/CuGaSe2/SnO2/glass thin film heterostructures annealed at different temperatures. The use of CuGaSe2 material in place of Cu(In,Ga)Se2 is only required by the indium diffusion studies. The CuGaSe2 layers were grown by close-spaced vapor transport for two types of sources having different grain sizes. The In2Se3 films were deposited by thermal evaporation. The heterostructures were annealed in vacuum at different temperatures and analyzed by secondary ion mass spectroscopy (SIMS). The copper, indium, and gallium SIMS concentration profiles show that the copper diffuses up to the In2Se3 film surface and that the indium can diffuse far away from the In2Se3/CuGaSe2 interface towards SnO2. The copper, indium, and gallium diffusions were studied and the interdiffusion parameters were computed. The simultaneous interdiffusions of copper and indium induces the formation of a p–n junction responsible for the photovoltaic effect of the Zn/In2Se3/CuGaSe2/SnO2/glass photocells, the SnO2 side being lighted. This hypothesis is supported by results carried out from electron beam induced current measurements, showing a notable shift of the junction from the In2Se3/CuGaSe2 interface through the CuGaSe2 layer in terms of the annealing temperature, resulting in an increasing of the photovoltages up to 650 mV.
Copper indium disulfide false(CuInS2false) thin films for photovoltaic applications were grown by close‐spaced vapor transport in a vertical reactor closed under vacuum. Solid iodine was used to provide the reagent. Optimal deposition conditions were determined by studying samples deposited on soda‐lime glass with X‐rays, scanning electron microscopy, energy‐dispersive spectroscopy, optical absorption, and Hall effect. The stoichiometry temperature range is relatively large compared to other I‐III‐VI compounds: the lower limit (∼370°) corresponds to the formation of CuI in the layers and the upper limit (∼680°C) is imposed by the glass substrate. No phase change was observed in this temperature range. All the layers are p‐type conducting, with carrier densities of the order of 1016 cm−3 and high mobility values in certain cases. © 2000 The Electrochemical Society. All rights reserved.
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