Avalanche multiplication noise characteristics in thin GaAs p/sup +/-i-n/sup +/ diodes

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.…”

Experimental evaluation of impact ionization in dilute nitride GaInNAs diodes

“…Also shown are the wafer positions at which measurements were taken, i.e., center ("c"), edge ("e"), or from center to edge ("c-e") of wafer. All wafers are as-grown, except for wafer E which is annealed at 850 C. thickness (w) measured by Li et al 9,15 It is evident from Fig. 2 that k ¼ b/a of GaInNAs is very similar to that of GaAs for N fractions 2.0%.…”

“…The w ¼ 0.4 lm p þ -i-n þ devices at the edge of wafer B, which contain 2.0% N, gave a k value (k ¼ 0.4) similar to that of a slightly thinner GaAs p þ -i-n þ diode, 15 as well as that of a slightly thicker GaNAs p þ -i-n þ diode with 0.75% N reported by Kinsey et al 5 Wafer A with w ¼ 1.0 lm and 1.0% N gave k ¼ 0.5, which is close to the k ¼ 0.6 of a GaAs diode with w ¼ 1.13 lm. 9 In contrast, for N content !3.0% the excess noise increases for both thin and thick GaInNAs structures as shown in Fig. 2, with an approximately two-fold increase in k compared with GaAs.…”

“…The avalanche gain or multiplication factor (M) is the ratio of the multiplied and primary photocurrent. The avalanche excess noise of the GaInNAs devices with a range of N compositions was measured using a phase-sensitive, transimpedance amplifier-based noise measurement system based on the method by Li et al 9 The system has a center frequency of 10 MHz and a stable effective noise power bandwidth of 5.43 MHz for device junction capacitances up to 100 pF.…”

Design and Distributed Computer Simulation of Thin p + –i–n + Avalanche Photodiodes Using Monte Carlo Model

“…If the primary photocarrier is a hole then k = α/β and if it is an electron then k = β/α. However, recent experimental measurements on GaAs APD's [3,4,5,6] have shown a significant reduction in excess noise factor as iregion thickness decreases below one micron. A carrier starting with near zero energy, relative to the band edge, will have an almost zero chance of having an ionizing collision until it has gained sufficient energy from the electric field to attain the necessary energy to permit impact ionization [7,8].…”