Defect characterization of GaAs/InP layers and MESFETs devices by admittance and photoluminescence spectroscopies

GaAs layers as well as GaAs MESFET devices on InP are studied by means of DLTS and PL spectroscopies. We correlate the compensation observed on the Si-n-doped GaAs layers to the incorporation of Si that moves from a Si Ga donor site to form a complex defect involving Si and As or Ga vacancies. A study of defects on MESFETs grown with various buffer layer thicknesses shows that the thicker this layer is the higher is the defect concentration. This behavior is assumed to be related to the compensation effect.