Growth of double doped semi-insulating indium phosphide single crystals

Semi-insulating (SI) InP, co-doped with a shallow acceptor (Hg or Cd) and a deep donor (Ti or Cr) has been grown by the gradient freeze method or by the liquid encapsulated Czochralski (LEC) technique. Three dopant couples have been studied: Hg+Ti, Hg+Cr and Cd+Cr. The crystals have been characterized by spark source mass spectrometry (SSMS), secondary ion mass spectrometry (SIMS) and thermally dependent Hall (TDH) effect using the Van der Pauw technique. Deduced from the activation energy measurements, the donor deep levels of titanium and chromium have been found to be at E_c-0.53 eV and E_v+0.56 eV, respectively. SIMS profiles on SI substrates annealed at 975°C show that SI InP (Ti, Hg) is more thermally stable than SI InP(Fe) and SI InP(Cr, Hg or Cd).