New semi-insulating InP: Titanium midgap donors

Abstract

Deep levels due to titanium were identified for the first time in InP and GaAs employing capacitance transients and optical absorption measurements. They were found to be Ti4+/Ti3+ donor levels at energies of 0.63±0.03 eV and 1.00±0.03 eV in InP and GaAs, respectively. The near midgap location of this donor level in InP is technologically very significant, since it provides a new means for obtaining semi-insulating InP with a resistivity of about 107 Ω cm. The thermal stability of Ti-doped InP should be superior to that of Fe-doped InP. A formulation involving the Ti dopant and shallow acceptor impurities for obtaining semi-insulating InP from the melt is presented.