Development of a Long-Wave Infrared Band-Edge Thermometry Instrument
Marquis, Jeremy Michael
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Accurate measurement of substrate temperature is one of the most critical process control parameters for molecular beam epitaxy (MBE) growth. Band-edge thermometry instruments have proven to be a valuable tool for process control during MBE growth of semiconductor films, providing as high as ±1 °C temperature resolution. The increasing use of InAs, GaSb, and AlSb III-V materials necessitates a method for accurately measuring the temperature of their lattice-matched GaSb substrates. Current-technology instruments typically rely on InGaAs detector materials which have a maximum wavelength λ detection of ~1.7 µm, but GaSb substrates have a band gap corresponding to > 2 µm wavelength. MBE growth needs a band-edge thermometry instrument capable of λ > 2 µm for process control. Such an instrument has been developed using an InAs/InGaSb strained-layer superlattice detector sensitive sensitive to 2-9.5 µm long-wave IR wavelengths.