Development of Si and SiO2 interfacial layers for growing photoconductive GaN on Au

Gallium nitride films deposited by high-temperature atomic layer deposition (HT-ALD) are

photoconductive. However, when deposited on Au, the GaN films are not photoconductive.

ALD on Au surfaces are non-photoconductive. The hypothesis is that at the high GaN deposition

temperature of 800 o C, Au diffuses into the GaN film, where Au acts as electron-hole

recombination traps. Alternatively, the depletion layer formed at the GaN/Au may penetrate

the entire GaN film, thereby rendering it non-photoconductive. To remedy the problem, a buffer

layer is proposed as a way of combating one or both issues. A 16 nm layer of Si was sputtered

onto Au thin films prior to HT-ALD of GaN. If Au diffusion into the GaN film is the issue, Au will

form a AuSi eutectic, where the Si is expelled to the GaN interface due to phase separation of

the AuSi eutectic. The inclusion of the Si buffer layer did produce photoconductive GaN that is

responsive to the visible range of the light spectrum. Scanning Electron Microscopy (SEM) and

Energy Dispersive X-ray Spectroscopy (EDS) were used to characterize the morphology and

elemental composition of the GaN film and the interface. The AC and DC electrical properties of

the GaN are also reported.