Deep traps in low-temperature grown non-intentionally doped bulk molecular beam epitaxial samples, and Si planar-doped molecular beam epitaxial samples, were identified by using thermally stimulated current spectroscopy. Thermally stimulated current spectroscopy was carried out on a low-temperature molecular beam epitaxial layer grown at 300C, and on a planar-doped layer with a nominal Si concentration of 3.4 x 1012/cm2. The non-intentionally doped bulk molecular beam epitaxial sample exhibited 3 peaks in the thermally stimulated current spectra, but the planar-doped molecular beam epitaxial GaAs samples exhibited spectra which were similar to those of bulk samples which were grown by using liquid-encapsulated Czochralski and vertical gradient freeze methods. Experimental evidence showed that the potential well which was present in the planar-doped sample was effective in detecting the presence of various deep traps which had not previously been seen in low-temperature grown bulk molecular beam epitaxial GaAs epilayers, due to a shorter carrier lifetime (about 10-12s) in the conduction band which occurred due to EL2-like deep-trap recombination. This was revealed by a large hopping conduction in low-temperature grown bulk molecular beam epitaxial GaAs at temperatures below 300K, but not in planar-doped molecular beam epitaxial GaAs because the 2-dimensional electron gas had a higher mobility than lateral low-temperature grown bulk molecular beam epitaxial GaAs layers.

Thermally stimulated current spectroscopy of silicon planar-doped GaAs samples R.M.Rubinger, J.C.Bezerra, E.F.Chagas, J.C.González, W.N.Rodrigues, G.M.Ribeiro, M.V.B.Moreira, A.G.De Oliveira: Journal of Applied Physics, 1998, 84[7], 3764-9