Fermi Level Effects on Dislocation Formation in InAs_1−xSb_x Grown by MOCVD.

Abstract

Dislocation formation in InAs_1−xSb_x buffer layers grown on InSb substrates by metal-organic chemical vapor deposition is shown to be reproducibly enhanced by p-type doping at levels exceeding the intrinsic carrier concentration at the growth temperature. To achieve a carrier concentration greater than 2 x 10¹⁸ cm⁻³, the intrinsic carrier concentration of InSb at 475 C, p-type doping with diethylzinc was used. Carrier concentrations up to 6 x 10¹⁸ cm⁻³ were obtained. The zinc doped buffer layers have proven to be reproducibly crack free for InAs_1−xSb_x step graded buffer layers with a final composition of x = 0.12 lattice matched to a strained layer superlattice (SLS) with an average composition of x = 0.09. These structures have been used to prepare infrared photodiodes. Details of the buffer layer growth, an explanation for the observed Fermi level effect and the growth and characterization of an infrared photodiode are discussed.