Characterization of defects in semi-insulating materials and heterojunctions.

摘要

A simpler and more reliable method of thermoelectric effect spectroscopy (TEES) was developed. We have found that the electrical contacts made on front and back surfaces of the sample are more reliable for the TEES measurement than both contacts made on the same surface. The temperature difference of about 1-2K between the back and front surfaces for about 500;The effects of the lattice-mismatch-induced defects on deep level traps in Ga;We applied different models to fit the temperature-dependent current-voltage characteristics in the as-grown and the annealed heterojunctions. The results showed that the thermionic emission and/or tunneling of the holes followed by an interface recombination are the dominant process in this material system, and the interface charge is the main factor affecting the hole conduction mechanism. The interface charge density in this material system is in the range of 1 to 7 ;A contact-related hole trap with an activation energy of 0.50-0.75eV was observed at the Al/GaInP interface. We attribute this trap to the oxygen contamination, or a vacancy-related defect, V