G.J. Qua

Demonstration of enhanced performance of an InP/InGaAs heterojunction phototransistor with a base terminal

The optical gain and the small-signal frequency response of an InP/InGaAs heterojunction phototransistor (HPT) with a base terminal are investigated in detail for the first time. When operated under an optimally chosen external base current, the optical gain is enhanced more than five times over that of the same device operated as a two-terminal device, over a 17-dB range of input optical power. The small-signal 3-dB bandwidth of the three-terminal device is enhanced 15 times over that of the two-terminal device over the same range of input optical power. For a pseudorandom NRZ bit stream at 100 Mb/s, a clear eye opening is observed at an incident optical power of -33 dBm (500 nW).<<ETX>>

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes

A theoretical model for the frequency response of InP/InGaAs avalanche photodiodes (APDs) is presented. Included in the analysis are resistive, capacitive, and inductive parasitics, transit-time factors, hole trapping at the heterojunction interfaces, and the avalanche buildup time. The contributions of the primary electrons, primary holes, and secondary electrons to the transit-time-limited response are considered separately. Using a measurement apparatus which consists of a frequency synthesizer and a spectrum analyzer controlled by a microcomputer, the frequency response of InP/InGaAsP/InGaAs APDs grown by chemical-beam epitaxy are measured. Good agreement with the calculated response has been obtained over a wide range of gains. >

High-speed InP/InGaAsP/InGaAs avalanche photodiodes grown by chemical beam epitaxy

High-performance InP/InGaAsP/InGaAs avalanche photodiodes (APDs) grown by chemical beam epitaxy are described. These APDs exhibit low dark current (less than 50 nA at 90% of breakdown), good external quantum efficiency (greater than 90% at a wavelength of 1.3 mu m), and high avalanche gain ( approximately=40). In the low-gain regime, bandwidths as high as 8 GHz have been achieved. At higher gains, a gain-bandwidth-limited response is observed; the gain-bandwidth product is 70 GHz. >

InP/InGaAsP/InGaAs avalanche photodiodes with 70 GHz gain‐bandwidth product

A wide bandwidth (8 GHz) and a high gain‐bandwidth product (70 GHz) have been achieved with InP/InGaAsP/InGaAs avalanche photodiodes (APD’s) grown by chemical beam epitaxy. These APD’s also exhibit low dark current ( 90% at λ=1.3 μm), and high avalanche gain (M0≂40).

Avalanche InP/InGaAs heterojunction phototransistor

We report on the characteristics of an avalanche InP/InGaAs heterojunction phototransistor. Below the turnover voltage, the gain is bias dependent and avalanching can be used to achieve significant ( \sim5\times ) improvement in the gain-bandwidth product. The noise current in this bias region has been measured and is shown to be predominantly shot noise of the photocurrent and the leakage current. Above the turnover voltage, negative resistance is observed and extremely high gains (>104) are achieved. In this mode, the pulse response is a narrow spike (rise time ≃ 20 ns) whose width is independent of the width of the incident optical pulse.

A monolithic long wavelength photoreceiver using heterojunction bipolar transistors

An optoelectronic integrated circuit (OEIC), consisting of a p-i-n photodetector and heterojunction bipolar transistors connected together as a transimpedance photoreceiver, has been fabricated. The monolithic photoreceiver was made from InP/InGaAs-based heterostructures and had a bandwidth of 500 MHz with a transimpedance of 1375 Omega . At a signaling rate of 1 Gb/s, the measured receiver sensitivity was -26.1 dBm at a wavelength of 1.5 mu m. A dynamic range greater than 25 dB and an equivalent input noise current of 11 pA square root Hz were also measured. >

The phototransistor revisited: all-bipolar monolithic photoreceiver at 2 Gb/s with high sensitivity

Summary form only given. The authors revisit the three-terminal phototransistor and demonstrate the application of the HPT (heterojunction phototransistor) at 2 Gb/s in an all-bipolar monolithic photoreceiver. They also show a performance comparable to the best p-i-n photoreceiver. The phototransistors were fabricated from epitaxial layers grown by metal-organic molecular beam epitaxy on a Fe-doped semi-insulating InP substrate. The phototransistor had a small-signal electrical current gain between 150 and 200. The quantum efficiency of the base-collector photodiode was 40%. Microwave on-wafer measurements yielded a unity current gain cutoff frequency of 30 GHz and a maximum oscillation frequency of 20 GHz at a collector current of 5.0 mA. The small-signal frequency response of the packaged monolithic photoreceiver indicated a 3-dB bandwidth of 1.1 GHz, at a wavelength of 1.53 mu m, with no peaking in the response. >

VB-7 InP/InGaAsP/InGaAs avalanche photodiodes grown by chemical-beam epitaxy

InP/InGaAsP/InGaAs avalanche photodiodes with sepa- rate absorption, grading, and multiplication regions (SAGM-APDs) have been fabricated from wafers grown by chemical beam epitaxy (CBE). These APDs exhibit low dark current ( 500-Mbit/s) lightwave sys- tems experiments have shown that avalanche photodiodes (APDs) can provide several decibels of improvement in receiver sensitivity compared to p-i-n photodiodes ( 11-(5). In long-wavelength (= 1.3- or 1.5-pm) lightwave receivers the highest sensitivities have been achieved with APDs having an InP multiplication region and an 1~,~~Ga,-,.~~As (subscripts deleted in following text) absorption region separated by a transition region consisting of one or more lattice-matched intermediate-bandgap In,Gal -,AsL.P1 -y layers, the separate absorption, grading, and multiplication regions (SAGM)- structure APD ( 11. To operate properly, the carrier concentra- tions and thicknesses of the different layers which comprise this structure must be controlled within very narrow tolerances (6). Although most of the SAGM-APDs that have been reported to date have been grown by liquid-phase epitaxy (LPE), the degree of precision and uniformity necessary to maintain the wafer parameters within the constraints required by this structure are difficult to achieve by this growth technique. Also, LPE is more difficult and more expensive to implement in large-scale production than vapor-phase tech- niques such as hydride vapor-phase epitaxy (VPE), metal- organic chemical vapor deposition (MOCVD), or molecular beam epitaxy (MBE). In the past, however, InP/In,- Gal-,As,P1-, photodetectors grown by MBE and MOCVD have not achieved performance characteristics as good as those grown by LPE due to the high background carrier concentra- tions of the In,Gal-,As,PI-, layers and the difficulty in achieving good InP/In,Gal -,As,P1 ->, interfaces. Recently, InPIInGaAsPiInGaAs SAGM-APDs grown by MOCVD (7) and VPE (8), (9) have been reported. In this paper we report on InP/InGaAsP/InGaAs SAGM-APDs grown by chemical beam epitaxy (CBE) (lo), a crystal growth technique that combines many of the advantages of MOCVD and MBE. A schematic cross section of the back-illuminated InP/