Noncontact observation of microdefects in GaAs doped with various impurities by photo-thermal-radiation microscope

The authors measured microdefects in GaAs doped with various impurities by a photo-thermal-radiation (PTR) microscope to investigate the nature of microdefects found in previous experiments. The samples used were Si-, S-, Te-, and Zn-doped GaAs wafers. The PTR signals were measured as a function of the wavelength of excitation light. The authors found a strong dopant dependence of the PTR spectra. The PTR signal has a clear maximum at λ≅900 nm only in Si-doped GaAs. The authors measured the PTR topographs in various GaAs wafers and compared them with photoluminescence topographs. The experimental results showed that the DTR technique gives important and unique information on the nonradiative microdefects in GaAs, although the nature of the microdefects is still uncertain