Semi-Insulating Behavior of InP Wafers Prepared by Phosphorus Vapor Pressure Controlled Wafer Annealing

Abstract

The semi-insulating (SI) behavior of InP wafers prepared with the phosphorus-vapor-pressure controlled annealing method has been investigated. Usually, the carrier concentrations in undoped InP wafers were decreased from the order of 10 15 to 10 14 cm --3 after annealing, but a prominent SI property was not obtained due to insufficient native deep levels for pinning the Fermi level. Transport properties of extremely low Fe doped InP wafers with Fe concentration of 1.5 Â 10 15 cm --3 were converted from conductive to semi-insulating after anneals of either at 950 C for longer than 20 h or at higher than 940 C for 40 h, under the phosphorus vapor pressure of 0.1 MPa. The compensation mechanism by Shockley will explain not only the electrical activation of Fe after annealing, but also the decrease of shallow donors which are related to native defects such as phosphorus vacancies. In this paper, effective annealing conditions for realizing the reproducible production of extremely low Fe doped SI InP have been investigated systematically. Furthermore, a compensation mechanism will also be proposed in connection with it.