Performance improvement of GaN-based metal–semiconductor–metal photodiodes grown on Si(111) substrate by thermal cycle annealing process

Abstract

A simple thermal cycle annealing (TCA) process was used to improve the quality of GaN grown on a Si substrate. The X-ray diffraction (XRD) and etch pit density (EPD) results revealed that using more process cycles, the defect density cannot be further reduced. However, the performance of GaN-based metal–semiconductor–metal (MSM) photodiodes (PDs) prepared on Si substrates showed significant improvement. With a two-cycle TCA process, it is found that the dark current of the device was only 1.46 × 10−11 A, and the photo-to-dark-current contrast ratio was about 1.33 × 105 at 5 V. Also, the UV/visible rejection ratios can reach as high as 1077.

Improved conduction in GaN Schottky junctions with HfO2 passivation layers through post-deposition annealing

“…aN-based Schottky junctions are essential functional building blocks for power switching circuits, this is attributable to the material's electronic properties such as its direct wide bandgap, high-electron mobility, high breakdown field, high saturation velocity, and robust radiation sensitivity. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] However, the drawbacks of conduction in GaN Schottky junctions such as current collapse, leakage current, and premature breakdown happen due to unavoidable surface defect centers located at threading dislocations on the GaN surface. [15][16][17][18][19][20] High-k dielectric thin films can effectively reduce surface defect states by compensating for surface dangling bonds and ions both physically and electrochemically.…”