Photocapacitive detection of hole emission from DX center in si-type Al_0.3Ga_0.7As doped with Te

Photocapacitance (PHCAP) measurements are applied to liquid-phase epitaxially grown n-Al_0.3Ga_0.7As crystals at different temperatures. The PHCAP measurements revealed deep levels optically located at 0.5 eV below the conduction band and 1.5 eV above the valence band [E_c -0.5 eV level (Te-related DX center) and E_c + 1.5 eV level]. The thermal activation energy of electron capture at the ionized E_c-0.5 eV level was found to be 31 meV. The optical hole emission process from the E_c + 1.5 eV level was enhanced with increasing sample temperature. After 1.5 eV monochromatic light preirradiation, the E_c - 0.5 eV level was detected in an intentionallly undoped n-Al_0.3Ga_0.7As sample. From these results, the structure of the Te-related DX center is discussed.