High speed InAs electron avalanche photodiodes overcome the conventional gain-bandwidth product limit

Abstract

High bandwidth, uncooled, Indium Arsenide (InAs) electron avalanche photodiodes (e-APDs) with unique and highly desirable characteristics are reported. The e-APDs exhibit a 3dB bandwidth of 3.5 GHz which, unlike that of conventional APDs, is shown not to reduce with increasing avalanche gain. Hence these InAs e-APDs demonstrate a characteristic of theoretically ideal electron only APDs, the absence of a gain-bandwidth product limit. This is important because gain-bandwidth products restrict the maximum exploitable gain in all conventional high bandwidth APDs. Non-limiting gain-bandwidth products up to 580 GHz have been measured on these first high bandwidth e-APDs.

High-Gain InAs Avalanche Photodiodes

“…17. Consistent with the measurements reported in [5] there is no evidence of a finite gain-bandwidth product, as would be expected for k~0.…”

“…On the other hand, the InAs APD in Ref. [5] has a depletion region of approximately 3 μm and the gain increases slowly, i.e., the gain is lower for the same bias, as shown in Fig. 10.…”

“…[6] follow the gain curve of the APDs reported here except the maximum gain is 20. Figure 11 shows that the depletion width for a given Depletion region thicknesses of UID and graded InAs APDs compared to the data in [5] and [6] (dash lines). bias is almost the same for the UID and graded structures.…”

Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping

“…In addition, by improving the molecular beam epitaxy growth conditions, we reduced the background doping concentration and realized depletion widths as wide as 5 lm at reverse biases as low as 1.5 V. These improvements culminated in low-noise InAs avalanche photodiodes exhibiting a room temperature multiplication gain of $80, at a record low reverse bias of 12 V. Over the past decade, InAs avalanche photodiodes (APD) have been shown to exhibit electron-dominated avalanche multiplication, 1,2 significant gain at low biases and electric fields, 3 near ideal excess-noise characteristics, 4 and gain-independent bandwidth. 5 InAs possesses several advantages compared to other APD materials, including strong optical absorption extending into the mid-infrared, inherent compositional uniformity, and mature high-yield III-V device fabrication. These characteristics make InAs APDs attractive for a wide range of applications including chalcogenide fiber-based and free-space optical communications, remote gas sensing, 3D laser detection and ranging (LIDAR), and both active and passive imaging.…”

Charge-compensated high gain InAs avalanche photodiodes

“…In Ref. [6] 15 V was required to obtain the same gain, an indication of enhanced gain in the charge-compensated 6 μm depletion region. Figure 4(b) shows the measured and simulated excess noise factor.…”