Ohmic and rectifying contacts for ultraviolet photodiode based on AlGaN solid solutions

A technology of Ti/Al contacts using thermal vacuum evaporation and further annealing in vacuum wasproposed. Contacts for Si-doped Al
_x
Ga
_1-x
N epitaxial layers (x = 0.08 - 0.7, n = 1.7 · 10
¹⁹
cm
^-3
) were fabricated and investigated. The Si-doped epitaxial layers were grown by plasma-assisted MBE and HVPE (x = 0.1, n = 10
¹⁶
- 10
¹⁹
) on c-sapphire substrates. The contact resistance of 8 · 10
^-5
Ω· cm
²
was achieved for the Al
_0.5
Ga
_0.5
N sample. Auger electron spectroscopy was used to study redistribution of metal atoms after annealing.