DX centers in si-doped In_xAl_1-xAs (0.3≤x≤0.5)

摘要

a multilevel donor model is developed, which takes into account the negative charge and the two-electron occu- pation probability of DX centers and also considers coexisting hydrogenic states. By solving Schrodinger's and Pois- son's equations self-consistently, this model is applied to calculate the sheet carrier density in metamorphic In_xAl_1-xAs/In_xGa_1-xAs HEMT structures on GaAs for indium contents x in the range 0.3≤x≤0.5. by comparing the Calculations with reported Hall data, the experimentally observed reduction of free carrier density for compositions With x below 0.4 is attributed to the trapping at DX centers. The ionization energies of Dx centers in the In_xAl_1-xAs System deduced for the investigated range of x are consistent with an extrapolation from data reported for compositions With 0＜x＜0.3.