Polarity of a (111)-oriented CdTe layer grown on a (100) Si substrate

Abstract

Direct epitaxial growth on silicon has advantages when fabricating monolithic integrated infrared focal-plane arrays. We demonstrated that both (111)A and (111)B oriented CdTe layers can be grown on (100) Si substrates by molecular-beam epitaxy. The surface morphology of the (111)A layer was rough, while that of the (111)B layer was smooth. The key determining polarity is the substrate temperature during preadsorption of Te2 flux. We found a polarity transition at 450 to 500 °C, and (111)B layers grow above that temperature.

Optical characterization of epitaxial single crystal CdTe thin films on Al2O3 (0001) substrates

“…While detectors are often fabricated from single crystals [1] , thin films are primarily used for commercial solar cells [2] due to processing costs and the lack of large diameter wafers of bulk CdTe. CdTe thin films have demonstrated a strong tendency towards polycrystalline growth that can lead to high defect densities, difficulty with doping, surface roughing, and an overall decrease in material quality, which limit all optoelectronic device efficiency [3]. Despite continued research efforts on polycrystalline CdTe solar cells, measured CdTe solar cell efficiencies are far below calculated theoretical efficiencies and are limited by grain sizes/boundaries, carrier mobility and carrier lifetime [4] , [5] .…”

Atypical grain growth for (211) CdTe films deposited on surface reconstructed (100) SrTiO3 substrates

“…Here, the addition of steps provides a mechanism able to promote one grain orientation at the expense of another [7,10,30]. An important example is the growth of CdTe on (1 0 0) silicon [30][31][32][33][34][35][36][37] where in the absence of steps there exist four equivalent grain orientations. The introduction of a miscut, however, introduces one-dimensional step-terrace structures that break the four-fold symmetry of the surface.…”

HgCdTe and CdTe(1̄ 1̄ 3̄)B growth on Si(112)5° off by molecular beam epitaxy

“…Both A and B faces can be grown on Si. 6 It depends on growth conditions, i.e., how we start the CdTe growth.…”

“…Te-Si bonding is, however, much stronger than Cd-Si bonding. 6 Tellurium atoms easily bond with Si at the ͑111͒ terrace, and this is a possible reason for A-face growth in normal and Cd-excess growths. Zn-excess growth, on the other hand, results in a B face, which is consistent with the work of de Lyon et al in which the insertion of a ZnTe buffer layer caused a B face.…”