THIN MULTIPLICATION REGION INALAS HOMOJUNCTION AVALANCHE PHOTODIODES

Low excess noise in avalanche photodetectors (APDs) is desired for imp roved sensitivity and high-frequency performance. Gain and noise chara cteristics an measured for InAlAs p-i-n homojunction APDs that were gr own with varying i-region widths on InP by molecular beam epitaxy, The effective ionization ratio k (beta/alpha.) determined by noise measur ements shows a dependence oil multiplication region width, reducing fr om 0.31 to 0.18 for multiplication region thicknesses of 1600-200 nm. This trend follows previously shown results in AlGaAs-based APDs, whic h exhibit reduced excess noise due to nonlocal multiplication effects. These results show that this effect is a characteristic of thin avala nche regions and is not a material-specific phenomenon. (C) 1998 Ameri can Institute of Physics. [S0003-6951 (98)00332-5].