All-optical transistor using deep-level defects in nitride semiconductors for room temperature optical computing

The essential device for optical computing is an all-optical transistor in which a weak “gate” light controls the strong “source” light. Particularly promising for application in logic operations are all-optical transistors using quasiparticles in a semiconductor because they can be easily integrated into circuits in a way similar to that of conventional electronic ones. However, the practical development of such devices has so far been limited due to extreme difficulties in achieving room temperature operation. In this work, we proposed and numerically verified a scheme of the high-temperature stable all-optical transistor, where light controls light by using deep-level defects in non-polar InGaN/GaN heterostructure and photo-exited holes as an intermediate medium. The developed optical switching concept fulfills all criteria for the useful all-optical transistor listed in Miller, Nat. Photonics 4, 3 (2010), in particular fan-out and cascadability, which are the most difficult to meet. For the design of our transistor, we applied an entirely new approach to III-nitride device physics: we turned usually undesirable deep-level defects into a key, active element of the transistor in which they realize on and off operations. Due to this, the developed device was able to obtain excellent operation stability in a wide temperature range up to 500 K as well as an extremely high on/off ratio (106) and gain (100). Finally, in order to show that the proposed transistor concept is feasible, we performed the gated-photoluminescence experiment for metal–oxide–semiconductor GaN structures.