Photothermal ionization spectroscopy of shallow donors in high purity LPE-GaAs

The photoconductive response spectrum of high purity epitaxial n-GaAs at 4.5K under the magnetic field strength of 0-8T has been performed by using technique of photothermal ionization spectroscopy. The residual shallow donor impurities of S and Sn in LPE n-GaAs and Sn and Pb in VPE n-GaAs are detected and identified. The results obtained show that the contamination of Si and Sn can be significantly reduced by using LPE techniques.