Abstract
Hg_<1-x>Cd_xTe epilayers were grown on CdZnTe substrates by molecular beam epitaxy (MBE). The Cd composition (x) ranges from zero band gap region (ZBG, x = 0.05〜0.18) to narrow band gap region (NBG, x=0.21〜0.29). Substrate orientations are (21l) A, (21l) B, (111) B and (110). First, crystallinity and morphology of epilayers with these four orientations are compared and HgCdTe (21l) B epilayer is found to have best property. Furthermore, twin formation mechanism is discussed, from a viewpoint of growth velocity. Second, Cd composition measurement method is presented and high uniformity of the composition over both surface and depth direction is confirmed for MBE-HgCdTe epilayers. Finally, from Hall effect measurement data for HgCdTe (21l) B epilayers, Hg vacancy formation energy, some indication of electrically compensated properties and carrier scattering mechanism are discussed. For the ZBG epilayers, clear dependence of electron mobility on Cd composition is presented and the maximum mobility is obtained for the x〜0.15 epilayers (just zero band gap at 77 K).
