Investigation of current-voltage characteristics of n-GaN/i-AlxGa1-xN/n-GaN structures

Although standard GaN device structures used for FETs, light emitters, and detectors have been investigated reasonably extensively, the device structures relying on the particulars of current transport over barriers in this material system have not received as much attention, to a large extend due to the insufficient quality of the layers. Unless special measures are taken, the defects present in the barrier material induce current conduction paths that preclude any possibility of observing the fundamental current conduction mechanisms. To overcome this impediment, high quality GaN layers, followed by the vertical single barrier heterostructures, have been grown on sapphire substrates using epitaxial lateral epitaxy in a metal organic chemical vapor deposition system with the aid of an in-situ deposited SiNx nanonet. Structural and optical properties of the films indicate their superior nature. With these templates in hand, n-GaN/i-AlxGa1-xN/n- GaN structures with varying barrier width and height have been prepared and tested for their IV characteristics. The rectification observed is consistent with the barrier design. Because the band bending is affected by polarization charge, which is dependent on pressure, current vs. voltage measurements under pressure have also been recorded. In this presentation, the details of the measurements and analyses, as well as the pertinent aspects of growth related issues will be discussed.