A mass spectrometric study of AsH 3 and PH 3 gas sources for molecular beam epitaxy

Abstract

The mass spectra of species resulting from the decomposition of AsH 3, PH 3 and a mixture of both have been studied with a modulated beam mass spectrometer. Two types of crackers, one that decomposes the hydrides at high pressure (∽200 – 2000 Torr) and one that decomposes them on a Ta catalyst at low pressure ( ⪷ 0.1 Torr) were used. Operating conditions that yield predominantly dimers are readily achieved with both sources although some monomer appears to be present in the flux from the low pressure source.