CdSe : In ‐ In2 O 3 Coatings with n‐Type Conductivity Produced by Air Annealing of CdSe‐In Thin Films

Abstract

Conversion of chemically deposited intrinsic CdSe thin films to n-type coatings by a postdeposition process is described. A Cd:Se-In thin film consisting of a CdSe thin film -0.15 p.m thick and a thermally evaporated indium film -0.02 p.m thick was air annealed at 325°C for 1 h. The resulting thin film coating of CdSe:In (0.15 p.m)-1n20,(0.03 p.m) exhibits a sheet resistance of 790 11/0 and an n-type conductivity of -400 fl' cm-' for the In,O, top layer. Etching of the film with 1 M HC1 for 6 h removes the superficial 1n203 from the coating, and the underlying CdSe with indium doping shows a sheet resistance of 15 kIll/fl which corresponds to electrical conductivity (n-type) of -0.4 fl' cm'. The composition of the film and its variation along the depth are established through analyses of x-ray diffraction pattern and xray fluorescence spectra as well as the photocurrent response of the annealed films recorded before and after chemical etching. InfroductionThe chemical bath deposition technique is a simple method for growing adherent, uniform, and specularly reflecting thin films, particularly of Il-VI semiconductors.' This technique has been used to deposit CdSe thin films from solutions containing a cadmium ion complex and either selenosulfate,2'3 (Na,SeSO,); selenourea , (NH2),CSe; or N,N-dimethylselenourea,' (C,H,N,Se); as the source of selenide. After an initial nucleation phase, ion-by-ion con-

Structural and Electrical Properties of Annealed In–Bi2S3Thin Films

“…Application of the films in solid state solar cells may also be a possibility. The present work supplements earlier results on chemically deposited CdS#In and CdSe#In films (8,9), suggesting that the chemical deposition technique may be combined with thermal evaporation of metallic films to produce coatings with interesting electrical properties.…”

Thin films of arsenic sulfide by chemical deposition and formation of InAs

“…that In 2 O 3 :Sn (indium tin oxide, ITO) is a transparent conductive coating with the high electrical conductivity of 10 3 -10 4 −1 cm −1 [36] and that in sub-stoichiometric (In 2 O 3−x ) material, the electrical conductivity can be relatively high, 10 −2 -10 2 −1 cm −1 . The latter aspect has been discussed in the case of heated layers of CdSe-In [37] and CdS-In [38]. In a 1968 paper, a carrier density of ≈10 24 m −3 and an electron mobility of 0.3 m 2 V −1 s −1 were reported for InAs thin films formed by thermal evaporation, which was annealed at temperatures 300 • C or above [39].…”

Semiconductor thin films by chemical bath deposition for solar energy related applications

“…Recently, we reported another technique to convert the chemically deposited CdS [57,58] and CdSe thin films to n-type [59]. Fig.…”

“…12 illustrates the basic mechanism involved. A 20 nm thick indium film is evaporated over a chemically deposited CdSe thin film of about 150 nm thickness [59]. The quantity of indium required for this is about 15 mg to cover an area of 150 cm of the film surface.…”