Effect of threading dislocations on mobility in selectively doped heterostructures grown on Si substrates

We studied the effect of threading dislocation scattering on the mobility of a two-dimensional electron gas. To verify our theory, we grew Si-doped AlGaAs/GaAs selectively doped heterostructures with different dislocation densities by changing the number of thermal annealing cycles. The theory agreed well with our experimental results. Previous work on high electron mobility transistors (HEMTs) fabricated on Si indicated that the device characteristics are insensitive to the dislocation density. Our theory states that the room temperature mobility reduction by dislocations with a density below 108 cm−3 does not affect HEMT device performance, which is consistent with empirically known results.