Large temperature changes induced by molecular beam epitaxial growth on radiatively heated substrates

Abstract

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 °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.

GaAs-substrate-based long-wave active materials with type-II band alignments

“…The coupling between the substrate and the substrate heater thermocouple is superior for doped materials. 6 The growths were done using dead reckoning under substrate heater thermocouple control with the thermocouple-substrate offset temperatures determined by pyrometry on the bare GaAs substrate before the growth was started. Run-to-run growth temperature reproducibility is very important when growing mixed group-V alloys because incorporation of a given group-V element is typically strongly temperature dependent.…”

Transport properties of Be- and Si-doped AlSb

“…11 Growth temperatures were measured by transmission thermometry. 12 Epitaxial layers were grown on semi-insulating ͑SI͒ GaAs͑001͒ substrates. Each sample consists of at least 3 m of AlSb, doped with Si or Be, and a 50 Å GaSb cap to prevent oxidation of the AlSb.…”

Surface reconstruction phase diagrams for InAs, AlSb, and GaSb

“…Furthermore, their calibration can change during growth of small-bandgap epilayers (e.g. InAs and GaSb), due to radiative heating that increases with "lm thickness [11,12]. The accuracy of optical pyrometry is limited by stray light from the substrate heater or source ovens, coating of the viewport, changes in substrate emissivity, and limited sensitivity below 5003C [13].…”