D.C.W. Lo

A monolithically integrated In/sub 0.53/Ga/sub 0.47/As optical receiver with voltage-tunable transimpedance

The authors report the fabrication and performance of the first monolithically integrated In/sub 0.53/Ga/sub 0.47/As receiver with voltage-tunable transimpedance. In this receiver, a SiN/sub x/ passivated p-i-n diode is integrated with an In/sub 0.53/Ga/sub 0.47/As transimpedance amplifier using multiple-etched steps to assist lithography and step coverage of the interconnection metallization. The p-i-n diode has an external quantum efficiency of 82% at a wavelength of 1.3 mu m and -5 V bias. Adjusting the gate bias of a narrow-gate feedback transistor gives the receiver a tunable transimpedance of 19-36 Omega , a responsivity of 17-30 kV/W, and an unequalized bandwidth of 90-130 MHz.<<ETX>>

Optically powered optical interconnection system

A wavelength-multiplexed optical interconnection system in which the electrical power is provided by an optical source is discussed. The optical power and data signals, operating at two different wavelengths, are multiplexed onto a single fiber at the local terminal, and demultiplexed at a remote terminal. The optical power is then converted to electrical power by an array of photovoltaic cells, providing bias control to a data-detection circuit. The system operates at 45 Mb/s, the remote receiver dissipates 2.6 mW, and there is negligible optical crosstalk between the power and data channels.<<ETX>>

Performance of In/sub 0.53/Ga/sub 0.47/As and InP junction field-effect transistors for optoelectronic integrated circuits. II. Optical receiver analysis

The authors have developed an analytical model to study In/sub 0.53/Ga/sub 0.47/As and InP junction field-effect transistors (JFETs) for use in InP-based optoelectronic integrated circuits (OEICs). This model includes the effects of channel resistance and band-to-band tunneling. The agreement between the calculations and experimental results supports the validity of the model. The authors discuss the optimum design for these JFETs and compare their performance quantitatively. In order to prevent device performance from being degraded by the effects of tunneling, the optimum channel dopings of In/sub 0.53/Ga/sub 0.47/As and InP JFETs are found to be 7*10/sup 16/ and 5*10/sup 17/ cm/sup -3/, respectively. In/sub 0.53/Ga/sub 0.47/As JFETs not operated in the tunneling regime show at least a 40% higher efficiency than InP JFETs in terms of the power dissipated per transconductance. The authors conclude that In/sub 0.53/Ga/sub 0.47/As JFETs are well suited for very-high-density monolithic integration, where power efficiency must be high. >

In/sub 0.53/Ga/sub 0.47/As junction field-effect transistors as tunable feedback resistors for integrated receiver preamplifiers

In/sub 0.53/Ga/sub 0.47/As active feedback junction field-effect transistors (JFETs) for use in integrated transimpedance photoreceivers are discussed. By varying the gate-to-source voltage V/sub GS/, the resistance can be continuously tuned between 3 and 40 k Omega with a drain-to-source capacitance of <10 fF. The temperature coefficient of resistance is between -5 and -20 Omega / degrees C (for V/sub GS/ less than the pinch-off voltage). The combination of large resistance and low capacitance can result in high receiver sensitivity without sacrificing amplifier dynamic range. The feedback FET was fabricated adjacent to 1.8- mu m-gate-length JFETs with transconductances of 110 mS/mm, gate-to-source capacitances of 1.3 pF/mm, and DC amplifier voltage gains of 100. The compatibility of these transistor structures indicates that an integrated preamplifier with dynamically tunable bandwidth can be realized.<<ETX>>

A high performance monolithic In/sub 0.53/Ga/sub 0.47/As voltage-tunable transimpedance amplifier

The fabrication and performance of the first monolithically integrated In/sub 0.53/Ga/sub 0.47/As JFET voltage-tunable transimpedance amplifier for use in InP-based optoelectronic integrated circuits are reported. A narrow-gate transistor is used as an active feedback resistor. The two-stage voltage amplifier has a voltage gain of 10.7 and a bandwidth of 350 MHz. The closed-loop transimpedance of the amplifier is tunable from 10 to 24 k Omega by controlling the gate bias of the feedback transistor.<<ETX>>

Narrow-gate In/sub 0.53/Ga/sub 0.47/As junction field-effect transistors as tunable resistors for long-wavelength integrated optical receivers

The fabrication of In/sub 0.53/Ga/sub 0.47/As junction field-effect transistors (JFETs) for use as active feedback resistors in integrated transimpedance photoreceivers is described. Transistors using both air-bridge and non-air-bridge technologies are described. Varying the gate-to-source voltage (V/sub GS/) allows the output resistance to be tuned continuously between 3 and 40 k Omega with a drain-to-source shunt capacitance of less than 10 fF. The temperature coefficient of the output resistance is between -5 and -20 Omega / degrees C (for V/sub GS/ less than the pinch-off voltage). The combination of large resistance and low shunt capacitance can result in high receiver sensitivity without sacrificing amplifier dynamic range. The feedback FETs are fabricated adjacent to 1.8- mu m gate JFETs with transconductances of 110 mS/mm and gate-to-source capacitances of 1.3 pF/mm. >

Gate tunneling current in In0.53Ga0.47As junction field‐effect transistors

Band‐to‐band tunneling leakage current is identified as the dominant source of dark current leakage at the gates of In0.53Ga0.47As/InP junction field‐effect transistors (FETs) optimized for use in linear, optoelectronic integrated circuit applications. Both the temperature and voltage dependencies of the gate leakage in such devices is studied, and the results are in agreement with calculations based on the FET two‐region model modified to include the effects of tunneling. Due to the fundamental nature of this leakage mechanism, and due to the fact that gate leakage induces shot noise, these results suggest that both low noise and high gain can be achieved by limiting the channel doping to ∼9×1016 cm−3 for FETs operated at a frequency of 1 GHz.

Gate tunneling current in In/sub 0.53/Ga/sub 0.47/As junction field-effect transistors

Data are presented which conclusively eliminate channel current impact ionization as the dominant source of gate leakage current in InGaAs JFETs based on both the temperature and channel current dependence. At the same time, strong evidence is presented which indicates that band-to-band tunneling at the gate-drain interface is the dominant source of gate leakage current. Based on these and previous results, it is concluded that InGaAs JFETs in linear preamplifiers such as optical receivers have an optimum channel doping of approximately 9*10/sup 16/ cm/sup -3/ at a bandwidth of 1 GHz. This value is obtained based on a tradeoff between gain, bandwidth, and noise.<<ETX>>