No abstract

The temperature dependences of the piezoelectric photo-thermal (PPT) signals from unintentionally doped p-type GaAsN films grown on semi-insulating GaAs substrate were measured from 80 to 300 K. From the theoretical analysis based on the rate equation for the recombination of photo exited carriers to the localized levels, we identified five majority hole traps, P1-P5 in GaAsN films. Among them, estimated concentrations of the P3 and P5 traps increased with the nitrogen contents. Therefore, we concluded that these two traps were due to nitrogen-related recombination centers in GaAsN.

The exciton binding energies (E xb) of a dilute nitride Ga1-y In y N0.012As0.988 layer (y = 0.0 to 4.5%) with the thickness of 100 nm were determined by both piezoelectric photothermal (PPT) and photoreflectance (PR) spectroscopies. Curve-fitting analyses were carried out using a three-dimensional direct allowed-transition model with the Voigt function as a convolution integral for PPT and with Aspnes' formula for PR. The observed estimation error for PR was about two times larger than that of PPT. Therefore, we conclude that PPT is a novel methodology for determining E xb when it is small and two expected critical energies exist in the narrow energy region.