Enhanced current transport in GaN/AlN based single and double barrier heterostructures

Abstract

Current transport through a unique structure design employing high quality GaN based heterostructure with sharp interfaces has been investigated. A novel approach of structure design has been adopted to enhance the current transport in GaN heterostructures with a specific number of barrier layers of AlN which includes Single Barrier Heterostructure (SBH) and Double Barrier Heterostructure (DBH) devices. The high band gap AlN can act as a barrier for current conduction between GaN layers and help in effectively enhancing the current transport in the device through tunneling phenomena. A highly enhanced current transport in comparison with No Barrier Heterostructure (NBH) has been observed in SBH and a further improvement is perceived in DBH. Moreover, the phenomenon of current conduction is explained through drift-diffusion model, in which current enhancement upon subsequent addition of high bandgap barrier layer has resulted in localized high electric field and thus charge carrier velocity overshoots. Further, this has also been explained via quantum model, by interference of transmitted and reflected electron wave at interfaces. UV photodetectors using such heterostructure designs with and without AlN barrier layers in metal-semiconductor-metal geometry have been fabricated. The UV photodetection device developed using DBH yields photoresponsivity 80 times higher as compared to NBH device under UV illumination (325nm). Employment of such structures will enable scaling up the production of highly efficient optoelectronic devices.