A Monte Carlo investigation of multiplication noise in thin p/sup +/-i-n/sup +/ GaAs avalanche photodiodes

Numerical Analysis of Homojunction Avalanche Photodiodes (Apds)

“…Since this ratio is a material property, for a given electric field, efforts to improve the APD performance have focused on optimizing the electric field profile and characterizing new materials. Recently, lower multiplication noise and higher gainbandwidth products have been achieved by sub micrometer scaling of the thickness of the multiplication region [4][5][6][7][8][9][10][11][12]. This is in direct contrast to what would have been predicted by the local-field model and is due to the nonlocal nature of impact ionization, which can be neglected if the thickness of the multiplication region is much greater than the "dead length", the distance over which carriers gain sufficient energy to impact ionize.…”

The merits and limitations of local impact ionization theory [APDs]

“…Hayat et al. [7] and more recently Ong et al [26] showed that the excess noise figures in thin structures were reduced below the local values when high fields cause determinism in the avalanche process, rather than low effective ratios. In our view, attempts to correlate the excess noise with effective ratios, such as those in [10], [27], are consequently misleading.…”

Gain-bandwidth product optimization of heterostructure avalanche photodiodes

“…As the multiplication region becomes thin (e.g., below 200 nm), the dead-space effect becomes progressively more pronounced because the dead space occupies a larger fraction of the multiplication region [11], [12]. The dead space is the minimum distance a carrier must travel in the high-field multiplication region before reaching the ionization threshold energy [13], [14].…”