L. R. Tomasetta

III-V alloy heterostructure high speed avalanche photodiodes

Heterostructure avalanche photodiodes have been successfully fabricated in several III-V alloy systems: GaAlAs/GaAs, GaAlSb/GaSb, GaAlAsSb/GaAlSb, and InGaAsP/InP. These diodes cover optical wavelengths from 0.4 to 1.8 \mu m. Early stages of development show very encouraging results. High speed response of 95 percent have been obtained. The dark currents and the excess avalanche noise will also be discussed. A direct comparison of GaAlSb, GaAlAsSb, and InGaAsP avalanche photodiodes is given.

Ion‐implanted InGaAsP avalanche photodiode

High‐quantum‐efficiency planar and mesa InGaAsP avalanche photodiodes have been fabricated by beryllium ion implantation. The implanted diodes, after suitable annealing, exhibited a very low dark current density of 4.0×10−6 A/cm2 at 10 V. The devices have 65% external quantum efficiency at 1.06 μm without an antireflection coating and a uniform avalanche gain of 12.

High sensitivity optical receivers for 1.0-1.4 µm fiber-optic systems

The performance of high-speed, high-quantum-efficiency GaAlAsSb avalanche photodetectors suitable for a 1.0-1.4 \mu m high-performance fiber-optical communication system is described. The incorporation of these APDs with state-of-the-art GaAs FET electronics can lead to hybrid integrated optical receivers with 10-20 times better sensitivity at a 100-MHz bandwidth than is available with germanium APDs.

1.0–1.4‐μm high‐speed avalanche photodiodes

High‐speed high‐quantum‐efficiency avalanche photodiodes (APD’s) are required in the 1.0–1.4‐μm wavelength range in order to exploit the superior optical fibers now available at these wavelengths. The GaAlSb heterojunction APD’s reported here have external quantum efficiencies of 60% (without antireflection coatings), risetimes of 60 ps, and pulse widths (FWHM) of 120 ps with no evidence of a ’’back porch’’. Uniform high‐speed avalanche gains of 20 have been achieved.

Ionization coefficients of Ga0.72Al0.28Sb avalanche photodetectors

The performance of an optical receiver depends heavily on the excess multiplication noise characteristics of the avalanche photodetector. The excess multiplication noise factor of an avalanche photodiode depends on the ratio of the electron and hole ionization coefficients. The ionization coefficients of 1.06‐μm photodiodes fabricated from Ga0.72Al0.28Sb have been measured. The results show a hole‐to‐electron ionization‐coefficient ratio of 2, which implies an excess gain noise factor F of 5.9 when the diode is operated at a gain of 10.

GaAlAs/GaAs heterojunction Schottky barrier gate CCD

A buried channel Schottky barrier gate GaAlAs/GaAs CCD is described. Device structures, fabrication techniques and results are discussed. Charge transfer efficiency of 0.9993 per transfer has been measured on these 30 gate (10 pixel) CCDs. Dark current was found to be about an order of magnitude lower in GaAlAs than in GaAs. The best Ga.78Al.22As device has between 2 to 4nA/cm2at room temperature.

State‐of‐the‐art performance of GaAlAs/GaAs avalanche photodiodes

Ga0.15Al0.85As/GaAs avalanche photodiodes have been successfully fabricated. The performance of these detectors is characterized by a rise time of less than 35 ps, an external quantum efficiency with an antireflection coating of 95% at 0.53 μm, and a microwave optical gain of 42 dB. The dark current density is in the low‐10−8‐A/cm2 range at one‐half the breakdown voltages, and rises to 1.1×10−4 A/cm2 at 42 dB optical gain.

100 W average power 10.6 µm isolator based on the interband Faraday effect in InSb

A 10.6 μm isolator based on the interband magnetic optical effect in InSb has been tested to throughput levels of 100 W average power. The interband isolator figure of merit (rotation/loss) has been shown to be nearly a factor of two greater than the optimum free carrier effect isolator. Employment of the isolator at a 10.6 μm laser radar field site has resulted in the improvement of frequency stability and Doppler resolution.

The evolution from components to integrated optoelectronics circuits

Recent improvements in fiber optic semiconductor components (i.e. lasers and detectors) will lead to the rapid deployment of fiber optic systems in the next few years. This does not, however, signal the end of research in semiconductor optoelectronics, but rather the opening of new and ultimately more widespread application of optoelectronic devices. New and powerful signal processing and data transmission functions will become possible by the marriage of optical and electronic functions on a single monolithic wafer. Applications will range from simple single channel integrated repeaters to repeaters with error correcting electronics and switching capabilities to complex distributed computer data bus networks capable of interconnecting dozens of the computers of the 1990s with a circulating data stream operating in excess of 100 Gigabits/sec.

Be implanted InGaAsP avalanche photodiode

High quantum efficiency planar and mesa InGaAsP avalanche photodiodes have been fabricated by beryllium ion implantation. The implanted diodes, after suitable annealing, exhibited a very low dark current density of 4.0×10-6A/cm2at 10 V. The devices have 65% external quantum efficiency at 1.06µm without an anti-reflection coating and a uniform avalanche gain of 12.