Multiplication noise of AlxGa1−xAs avalanche photodiodes with high Al concentration and thin multiplication region

We report that homojunction AlxGa1−xAs avalanche photodiodes (APDs) exhibit very low multiplication noise when the Al content is ⩾80%. It was also found that, due to nonlocal effects, the multiplication noise decreased as the ionization region thickness was reduced from 0.8 μm to ⩽0.2 μm for Al ratios (from 0 to 0.9). The excess noise factor of the thin (140 nm) Al0.9Ga0.1As APDs is the lowest reported to date for III–V compounds and is comparable to that of Si avalanche photodiodes.