ELECTRICAL CHARACTERIZATION OF LOW-TEMPERATURE AL0.3GA0.7AS USING N-I-N STRUCTURES

Through temperature-dependent conductivity measurements, we show evide nce of a deep trap level in low-temperature (LT) Al0.3Ga0.7As layers w ith an activation energy of similar to 0.96 eV. This energy is near th at of EL2-like defects found previously in ''normal'' epitaxial Al0.3G a0.7As. It is also considerably larger than the 0.70 eV value typicall y associated with defects in LT GaAs, which may explain the observed l arge resistivity (> 10(11) Ohm cm) in LT Al0.3Ga0.7As. Current transie nt spectroscopy (CTS) of these samples yields a deep level activation energy of 1.01 eV, in close agreement with the value obtained from con ductivity measurements. (C) 1996 American Institute of Physics.