The preparation and assessment of indium phosphide

Abstract

Polycrystalline ingots of indium phosphide with large grain size have been grown by horizontal directional freezing in an autoclave. The best products have carrier concentrations <5×10 15 cm -3 at room temperature, and mobilities ranging from 20,000–40,000 cm 2 V -1 s -1 at 77 K. Pressure within the sealed silica ampoule was monitored throughout each run and the signal used to maintain a constant pressure of phosphorus during crystallization; the use of published vapour pressure equations to calculate pressure from the measured temperature of phosphorus zone proved to be unsatisfactory. The concentrations of silicon and certain other trace elements in the products have been determined by atomic absorption spectrophotometry, although the sensitivity of the analytical method was not adequate for the detection of silicon in products with carrier concentrations less than 1×10 16 cm -3. A comparison has been made between analyses of indium starting material, ingots of polycrystalline indium phosphide grown from an excess of the indium, and single crystals grown from the ingots by the LEC technique.