Enhancement of electron impact ionization in a superlattice: A new avalanche photodiode with a large ionization rate ratio

Abstract

The first superlattice avalanche photodiode (APD) is reported. The high field region of this p-i-n structure consists of 50 alternating Al0.45Ga0.55As (550 Å) and GaAs (450 Å) layers. A large ionization rate ratio has been measured in the field range (2.1–2.7)×105 V/cm, with α/β≃10 at a gain of 10 giving a McIntyre noise factor Fn = 3. The ionization rate ratio enhancement with respect to bulk GaAs and AlGaAs is attributed to the large difference in the band edge discontinuities for electrons and holes at the heterojunction interfaces. The superlattice APD is a new device concept which can be used to develop low noise APD’s in a variety of III-V materials including long wavelength 1.3–1.6-μm semiconductors.

Avalanche noise characteristics of single Al/sub x/Ga/sub 1-x/As(0.3<x<0.6)-GaAs heterojunction APDs

“…4-6. The claims by Chin et al [2], and by others [3]- [7] that heterojunctions could be used in avalanche regions to reduce excess noise by tailoring the ratio via the band-edge discontinuity, have not been borne out [8]- [17]. Indeed, increasing the aluminum fraction above and hence band-edge discontinuity actually increases excess noise, as shown in Figs.…”

“…Choice of the layer heterostructure could therefore influence the value of which controls the degree of noisy feedback processes [1]. Subsequent experiments by numerous authors variously supported [3]- [7] or disagreed [8]- [15] with these predictions. However, the most compelling evidence comes from Chia et al [16], [17], who compared multiplication in both homojunction and single heterojunction Al Ga As-GaAs p -i-n diodes and found that the multiplication in heterojunction diodes, and hence the ionization coefficients, were not enhanced over those of corresponding homojunction diodes.…”

The InAs Electron Avalanche Photodiode

“…Until recently the optimum case, where k = 0, remained an unachievable theoretical ideal, with most materials exhibiting 0.1 < k < 1. Indeed, unable to identify sufficiently capable materials, some researchers resorted to trying to engineer superlattice structures in which the ionisation coefficients were more disparate (Capasso et al, 1982;Yuan et al, 2000). Beck et al were the first to report APD characteristics consistent with k = 0 in 2001, when they reported results from Hg 0.7 Cd 0.3 Te APDs (Beck et al, 2001).…”

Transient Transport in Binary and Ternary Semiconductors.

“…(19), it is assumed that [ABI is a c-number in- (13) dependent of the eigenvalues A' and B'. We define Since (A'IeitA IA") = e i EA'6(A' -A") in theA'-rep-F(A', B'), the generalized Wigner distribution funcresentation, CA (Q) in eq.…”