Pressure Studies of Impurity Levels in AlxGa1-xAs

摘要

It is well known that the application of hydrostatic pressure moves the conduction bands (CB) in Gallium Arsenide in a manner similar to alloying with Aluminum Arsenide: the initial Gamma-L-X ordering changes to X-L-Gamma both with higher Al composition and with hydrostatic pressure. We present a study of Al(x)Ga(l-x)As (with approx. 10 to the 15th power/cu cm silicon) up to a pressure of 60 kbar at temperatures between 15 and 125 K using photoluminescence (PL) spectroscopy. Shallow donor levels that manifest themselves both via bound exciton (BE) and donor-acceptor (DA) recombination are observed at low pressures, where the lowest CB is still at Gamma BE and deep donor-to-acceptor recombination are seen at higher pressures where the lowest CB is at X. At a few pressures chosen to be typical of Gamma and X, we study the temperature evolution of the PL spectrum and its dependence on excitation intensity. We obtain activation energies and thereby an energy level scheme for the sample as the lower CB changes from Gamma to X. Keywords: Semiconductors; Substrates; Molecular beam epitaxy; Reprints. (aw)