Electrical and optical characterization of n-GaAs grown by MOCVD on semi-insulating InP and application to defect studies on MESFETs devices

The lattice-mismatch of 4% between GaAs and InP does not preclude device fabrication, although the characterization of such materials has shown the existence of a high density of dislocations at the heterointerface and a residual biaxial tensile strain due to the difference between the thermoelastic properties of the two materials. These growth difficulties are very detrimental for device applications and mainly for minority carrier based ones since they kill their lifetime. A compensation phenomenon on GaAs/InP samples is observed compared to GaAs homoepitaxial layers. The authors performed deep level transient spectroscopy (DLTS) and photoluminescence (PL) experiments on GaAs/InP layers and MESFET devices. This work showed no direct evidence of the impact of the electrically active lattice mismatch induced defects on the compensation phenomenon in GaAs/InP epilayers. On the contrary, PL results revealed that the compensation mechanism could be interpreted as related to Si moving from a Ga donor site to form a complex defect associating Si and As or Ga vacancies.<
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