LARGE TEMPERATURE-CHANGES INDUCED BY MOLECULAR-BEAM EPITAXIAL-GROWTH ON RADIATIVELY HEATED SUBSTRATES

We have performed optical transmission measurements on radiatively heated GaAs substrates as a function of molecular beam epitaxial growth of InAs, GaSb, AlSb, and GaAs films. The energy gap of the GaAs substrate is observed to decrease strongly in energy when materials with band gaps smaller than GaAs are deposited. This decrease in energy gap is a consequence of a substantial increase in growth temperature induced by the deposition of the film. We have observed increases in temperature of over 150-degrees-C from the temperature measured before film growth. Because the thermocouple is weakly coupled to the radiatively heated substrate, conventional temperature controllers are ineffective at measuring or accounting for this change in temperature.