III-V Based Semiconductor THz Detectors

The III-V semiconductor materials have been investigated for use in the terahertz range, and results are reported on heterojunction and homojunction detectors. Broad response out to 1 THz has been observed in both Nitride and Antimonide based detectors. A responsivity R of ~2.5 AAV in 1-5 THz range was observed for a GaN detector. A stronger narrower response was also observed around 6 THz due to impurity ionizations. By changing the Al fraction in the Arsenide based detectors, free-carrier response was adjusted to have a threshold frequency in the range of 2.3-20 THz. Extension of this approach to Antimonide materials could allow free-carrier detectors with thresholds near 1 THz. The mechanisms of operation in these detectors will be discussed, and potential advantages and disadvantages of the materials will be considered. Among these is the increased control in tailoring the workfimction in Antimonides, and increased THz absorption in the Nitrides. The relative advantages of n-vs. p-type structures for the THz region will also be compared. This work was supported in part by the US NSF under grant #ECS-0553051.