Substrate temperature change in III–V molecular beam epitaxy

Abstract The surface temperature ( T s ), as inferred by desorption mass spectrometric determination of the Ga desorption rate, was followed in time after instantaneous changes were made in the setpoint temperature ( T stpt ) during molecular beam epitaxy (MBE) growth of GaAs. Comparison between the time-evolution of T s and that of the non-contact thermocouple-indicated temperature ( T TC ) shows that large T s overshoot is likely to occur under typical MBE growth conditions. Such T s overshoot can lead to significant compositional grading at nominally abrupt heterojunctions. Details of how T s evolves in time are found to depend on substrate conductivity, temperature controller settings (proportional band, integral, derivative), and maximum heater current setpoint.