Boron and nitrogen im gallium phosphide grown by the liquid encapsulated czochralski process

Abstract

Boron and nitrogen concentrations have been determined, using charged particle activation analysis, in a number of GaP ingots grown by the Liquid Encapsulated Czochralski process in order to determine the extent of the chemical interaction between the Gap melt and the liquid B2O3 encapsulant, and the nitrogen ambient used to pressurize the crystal puller. The effects of deliberate oxygen, nitrogen and boron doping have also been investigated. Boron concentrations have been found in the range 3 x 1018 to3 x 1018 cm-3, and boron incorporation is seen to be suppressed by the presence of oxygen and nitrogen. Channeled nuclear reaction and local mode absorption measurements have shown that the boron is predomin-antly located on substitutional gallium sites. The nitrogen gas used to pressurize the crystal puller results in nitrogen incorporation in the range 1–2 × 1017 cm−3. Comparison with optical absorption measurements indicates that the formulas used to determine nitrogen from optical measurements overestimate the nitrogen by a factor of 4.