CMOS Integrated 32 A/W and 1.6 GHz Avalanche Photodiode Based on Electric Field-Line Crowding

Abstract

This paper presents a new Si CMOS linear-mode avalanche photodiode (APD) based on an electric field distribution formed by field-line crowding. In this structure, a spherical avalanching electric field is enforced by field-line crowding due to the curvature of the half-sphere cathode (n-well). The electric field extends radially and, therefore, the entire lowdoped epitaxial layer serves as charge collection zone. This APD can provide high responsivity and bandwidth due to its thick absorption zone and drift-based carrier transport. Measurements using a 675 nm laser source at 200 nW optical power show a maximum bandwidth of 1.6 GHz while the responsivity is 32 A/W. In addition, a maximum responsivity of 3.05×10 3 A/W at 5 nW optical power is achieved. Due to the high avalanche gain, large bandwidth, and CMOS compatibility without any process modification, this APD is a promising optical detector for many applications.Index Terms-Avalanche photodiode (APD), field-line crowding, CMOS integrated photodetector, spherical avalanching field.

Area and Bandwidth Enhancement of an n+/p-Well Dot Avalanche Photodiode in 0.35 μm CMOS Technology

“…The light source is calibrated to provide a constant optical power of 2 nW over the spectrum using an optical power meter and a coupled variable optical attenuator. It can be seen that at = 675 nm and op = 2 nW, the responsivity of 0.27 A/W is achieved, which is as expected since the unamplified responsivity is independent of the optical power [ 25 ].…”

“…Ref. [ 25 ] used the field-line crowding concept with a small n + /n-well structure to form a distributed electric field over the whole diode volume to guide the photo-generated carriers in the peripheral volume. This device was realized in 0.18 µm CMOS with a 24 µm thick low-doped epitaxial layer.…”

A Near-Infrared Enhanced Field-Line Crowding Based CMOS-Integrated Avalanche Photodiode

“…6(a) shows the responsivity as a function of the reverse bias voltage at a low optical power (op) of 2 nW, obtained from the photocurrent characteristics, where the dark current has been subtracted. It can be seen that this APD shows almost the same responsivity for λ = 850 nm as it was obtained for λ = 675 nm in [30]. An unamplified responsivity (M = 1) of 0.42 A/W for 850 nm at V 0 = 1 V is achieved, which corresponds to the quantum efficiency of 61.4%.…”

“…Recently, we presented a new Si CMOS APD based on the field-line crowding concept, which can be fabricated in a standard CMOS process without any process modification [30]. The EFLC-APD possesses a small hemispherical multiplication region around the n-well/p-epi junction and a thick depleted volume in the p-epitaxial layer with a lower electric field to guide charge carriers from the whole diode volume towards the multiplication region.…”

Design and Simulation of a Novel Avalanche Photodiode Utilizing Field Effect Diode Structure

“…the dependency of the R (A/W) and QE (%) to the wavelength have been calculated [ 20,21 ] and drawn in Fig. 8.…”