MOVPE growth of magnesium cadmium sulphide: rocksalt or sphalerite?

• Published in: Journal of crystal growth 1997-01, Vol.170 (1-4), p.528-532
• Main Authors: Poole, I.B., Ng, T.L., Maung, N., Williams, J.O., Wright, A.C.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(96)00644-6

Epitaxial MgS has been grown by the MOVPE process using bis(methylcyclopentadienyl)magnesium and tertiarybutylthiol precursors on both GaP and GaAs substrates. For substrate temperatures between 450 and 550°C epitaxial layers possessing the rocksalt (NaCl) crystal form were produced. At lower temperature polycrystalline layers resulted. The absence of the previously reported sphalerite (zincblende) phase can be attributed to a combination of the high substrate temperatures employed and the choice of sulphur precursor rather than the effect of substrate mismatch. Additionally dimethyl cadmium was used to produce magnesium cadmium sulphide layers. Low concentrations of cadmium (x ≤ 0.08) resulted in homogeneous Mg1−xCdxS alloy epilayers. For x ≥ 0.14 polycrystalline material was produced. Similar isovalent Mg doping of hexagonal Cd1−yMgyS produced an upper limit of y ≤ 0.18 for single crystal alloy growth.