Ion-pairing between lithium and the residual acceptors in GaSb

Abstract

The electrical properties of p-type GaSb containing lithium have been measured over the temperature range 20–400°K. It is found that introduction of lithium by diffusion at temperatures below 500°C results in reduced hole concentrations and increased Hall mobilities. In addition, the residual acceptor level at approximately 0.03 eV characteristic of pure material, apparently disappears and is replaced by a shallow acceptor level. This behavior is taken as evidence for the formation of ion pairs between lithium donors and doubly charged residual acceptors. Introduction of lithium by diffusion at 600°C and subsequent heat treatment at lower temperature results in the formation of a large density of holes (> 1 × 10 18 cm −3) associated with a shallow level, suggesting the presence of substitutional lithium.