Cd self-doping of CdTe polycrystalline films by co-sputtering of CdTe–Cd targets

Abstract

Cadmium self-doped CdTe polycrystalline films were grown on Corning glass substrates at room temperature by cosputtering from a CdTe-Cd target. The electrical, structural, and optical properties of the films were analyzed as a function of the Cd concentration. Films with a stoichiometric composition, and slightly below and above it, were prepared. In films where the Te exceeds 50 at. %, it is found segregation of Te and its electrical resistivity is about 10 7 ⍀ cm. In those with an excess of Cd, the electrical resistivity drops several orders of magnitude, the carrier concentration increases, and the resistivity activation energy drops. From these results, we concluded that using this deposition method, n-type Cd self-doped CdTe polycrystalline films can be produced.

Structural and optical properties of Cu-doped CdTe films with hexagonal phase grown by pulsed laser deposition

“…All spectra showed the CdTe longitudinal optical (LO) mode at the frequency of 166.5 cm −1 and their second order (2LO) mode at 333 cm −1 , characteristic of CdTe. 6 The LO modes of cubic and hexagonal phases of CdTe can coincide at the same frequency, 13 so these measurements agree with those of XRD. The features located at 123 and 142 cm −1 correspond to the phonon vibrations A 1 and E 1 modes, respectively, in the hexagonal Te structure.…”

“…The features located at 123 and 142 cm −1 correspond to the phonon vibrations A 1 and E 1 modes, respectively, in the hexagonal Te structure. 6,14 The Te characteristic signals appears well defined in 2a) and 2c) spectra and weaker but still noticeable in 2b) spectrum. The Raman measurements indicate that undoped and Cu-doped CdTe films grew with an excess of Te.…”

“…Because the stable phase of CdS is the hexagonal phase is very important to obtain CdTe in hexagonal phase. CdTe polycrystalline films can be prepared by several growth techniques such as closespace sublimation (CSS), 4 chemical deposition, 5 sputtering, 6 pulsed laser deposition (PLD), 7 vapor transport deposition (VTD), physical vapor deposition (PVD), spray deposition 1 among others. Some of these techniques, such as CSS, VTD, PVD requires a high growth temperature.…”

Micro‐Raman study of laser damage in CdTe

“…The Raman spectra were recorded in backscattering geometry at room temperature, using either a 64000 Jovin Yvon spectrometer with the 515 nm argon laser line or a Bruker RFS 100/S spectrometer with the 1064 nm Nd:YAG laser line. The power densities were at least ~10 3 In (c) previous to recording the spectra the sample was exposed to the same radiation for 30 min.…”

“…Shin et al [1] have attributed them to Te precipitates present as a part of growth process of CdTe. Picos-Vega et al [3] studied CdTe samples grown either with Cd or Te excess and observed in Te rich material Te related optical modes at 123 cm -1 and 142 cm -1 , whereas in Cd rich material modes at 167 cm -1 and 334 cm -1 were measured. The authors concluded that the Te modes were due to small Te aggregates related with poor stoichiometry and disappeared gradually with the increase of cadmium content.…”