Electrical properties of InAlAs/InGaAs modulation doped structure after SiN passivated annealing

Abstract
The effect of thermal annealing on the InAlAs/InGaAs modulation-doped structure, passivated with a SiN film, was investigated. In contrast to the capless sample, the passivated modulation-doped sample exhibited negligible degradation in the two-dimensional electron gas concentration (NS) after annealing at 280 °C, indicating that SiN is an efficient passivation material to ensure good thermal stability for the InAlAs/InGaAs modulation-doped structure. In addition, partial recovery in NS was found by annealing the SiN-passivated sample that had experienced serious NS degradation. A series of secondary ion mass spectroscopy (SIMS) measurements and Hall effect measurements revealed that the recovery of NS is associated with the discharge of fluorine atoms from the Si-doped n-type InAlAs layer.