Impact ionization coefficients of Al0.8Ga0.2As

The impact ionization coefficients in bulk Al0.8Ga0.2As have been determine d from photomultiplication measurements over the electric field range of 32 8-519 kV/cm. Unlike in AlxGa1-xAs (x less than or equal to0.6), where the e lectron to hole ionization coefficients ratios (1/k) are less than 2, the 1 /k value in Al0.8Ga0.2As was found to be greater than 10. Excess noise meas urements corroborated the multiplication results, suggesting that this mate rial may be a suitable multiplication medium for low noise avalanche photod iodes. (C) 2000 American Institute of Physics. [S0003-6951(01)04501-6].