Low avalanche noise behaviour in bulk Al0.8Ga0.2 As

We report avalanche multiplication measurements on 1 μm thick bulk Al_0.8Ga_0.2As diodes which exhibit low excess noise. A series of homojunction p-i-n and n-i-p structures with very low dark currents of ~4 μA/cm² at 0.95 V_bd were characterised. Photo-multiplication measurements suggest that M_e >M_h with a k value of ~0.2, smaller than those reported in other bulk m-V materials, such as GaAs, GaInP, InP and Al _xGa_1-xAs(x⩽0.6). Excess noise results corresponding to k≈0.15 were obtained for electron initiated multiplication. This broadly corroborates the multiplication measurements and suggests that even in these 1 μm thick structures some non-local ionization behaviour may be helping to further reduce the excess noise measured