Photoreflectance And Photoinduced Microwave Reflectance Studies Of Surface Band Bending In Mg-Doped Inn

Photoreflectance (PR) and microwave-reflectance photoconductivity-decay (mu-PCD) have been applied to study the surface band bending in Mg-doped InN layers with various Mg concentrations (similar to 1x10(17) to similar to 7x10(19)cm(-3)) and thicknesses (similar to 400 to similar to 3600nm). A PR resonance related to the band-to-band transition at the Gamma point below the surface electron accumulation is observed for moderately doped samples ([Mg]: 1.3x10(17)cm(-3) to 8.7x10(17)cm(-3)). Samples with the Mg doping concentration in the range of similar to 5x10(18)<=[Mg]<= 7x10(19)cm(-3) are p-type and show very weak or no PR resonance. It is shown that the results correlate with the surface layer depletion thickness. The strongest PR signal is observed for thick depletion layers. The results are confirmed by mu-PCD measurements that show the longest carrier lifetimes for moderately doped samples with the thickest surface depletion layer.