Leye Aina

Band‐gap determination by photoreflectance of InGaAs and InAlAs lattice matched to InP

Photoreflectance‐derived band‐gap parameters as a function of temperature for InGaAs and InAlAs lattice matched to InP are reported. The experiment was performed on a set of samples of various compositions (and strains) yielding greater reliability and ensuring self‐consistency. For InGaAs, fits to the Varshni equation gave E0(T=0 K)=803 meV, α=4.0×10−4 eV K−1, and β=226 K. For InAlAs, E0(T=0 K)=1.541 eV, α=4.7×10−4 eV K−1, β=149 K, and Δ0=338 meV.

Photoluminescence from AlInAs/InP quantum wells grown by organometallic vapor phase epitaxy

Photoluminescence from AlInAs/InP quantum wells and single heterojunctions is reported for the first time. An emission centered around 1.1 eV which is most intense in multiquantum well structures, is shown to originate from confined‐particle transitions involving spatially separated electrons and holes in quantum wells in the InP and AlInAs, respectively. The AlInAs/InP heterostructure is shown to have a staggered band lineup with an effective band gap of 1.06 eV.

OMVPE growth of AlInAs and device quality AlInAs-based heterostructures

Abstract High-quality AlInAs exhibiting excellent photoluminescence and having residual electron concentrations as low as 7×10 15 cm −3 with electron mobilities as high as 1900 cm 2 /V·s has been grown by OMVPE. AlInAs/InP heterostructures are shown to be type II heterojunctions with electron mobilities as high as 4500 cm 2 /V·s at 300 K. This material was used for the fabrication of high-gain heterostructure MESFETs and heterostructure insulated-gate FETs (HIGFETs). AlInAs/InP MESFETs have DC transconductances as high as 220 mS/mm and microwave gains as high as 11.5 dB at 10 GHz with an max of 42 GHz. AlInAs/InP/GaInAs HIGFETs, however, show high transconductances up to 470 mS/mm at 300 K and 530 mS/mm at 77 K. These are some of the highest performance FETs fabricated on OMVPE-grown material.

Modulation‐doped AlInAs/InP heterostructures grown by organometallic vapor phase epitaxy

We have grown modulation‐doped AlInAs/InP heterostructures with two‐dimensional electron gases. Hall measurements and Shubnikov‐de Haas oscillations observed in these heterostructures yield electron mobilities as high as 26000, 9000, 2300 cm2/V s at 2, 77, and 300 K, with electron concentrations as high as 1.5×1012 cm−2. These results demonstrate the potential of the AlInAs/InP heterostructure for power microwave applications.

High mobility AlInAs/InP high electron mobility transistor structures grown by organometallic vapor phase epitaxy

We have grown single and double‐channel AlInAs/InP modulation doped heterostructures with electron mobilities as high as 5000 and 27 000 cm2/V s at 300 and 77 K, respectively. The sheet electron concentrations for these structures range from 1.5×1012 to 5×1012 cm−2. The layers exhibit strong Shubnikov de Haas oscillations, from which we determined two‐dimensional electron gas mobilities at 1.8 K of 40 000 cm2/V s. The electrical properties of the AlInAs/InP heterostructures are the best reported for any device structures with InP as the active layer material.

Electron mobilities of AlInAs and AlInAs/InP heterostructures

Electron mobilities at 300 K as high as 4500 and 9800 cm2 /V s are observed when AlInAs is grown on in situ‐grown InP and GaInAs, respectively. These high anomalous mobilities, compared to those of material grown directly on InP substrates, are shown to be due to parallel conduction both in the AlInAs and in the two‐dimensional electron gas present at the AlInAs/InP and AlInAs/GaInAs interface. To our knowledge, this is the first report of a two‐dimensional electron gas for AlInAs/InP heterostructures. Theoretical estimation of the electron mobilities in AlInAs using realistic values of alloy scattering potentials have been used to show that the true mobilities of electrons in AlInAs are for material grown on InP substrates.

MOVPE of AlInAs HEMT structures

Abstract The growth by MOVPE and device applications of AlInAs HEMT structures have been reported by several groups over the past few years. This paper reviews the technological achievements up to date, presents recent results on AlInAs HEMTs and discusses future requirements and approaches to the growth of AlInAs HEMT structures suitable for high frequency applications.

Linear-mode single photon counting APD arrays with subnanosecond, afterpulse-free performance for ladar, spectroscopy, and QKD applications

Epitaxial Technologies has developed a single photon counting photoreceiver that can operate in the linear mode to avoid the drawbacks of Geiger mode detectors. The Companys linear single photon counting photoreceiver array technology is based on cascading optical amplifiers on-chip with APDs to enable single photon capability below the APD breakdown voltage through ultra-low noise gain and preamplification. We have already demonstrated components for this photoreceiver that when implemented will have single photon sensitivities for subnanosecond pulses with high photon counting efficiency and without afterpulsing at 1064 and 1550-nm.

InP-based multiwavelength QWIP technology

This paper describes the design, growth and fabrication characterization of novel multi-wavelength QWIP wafers based on InP material systems. We designed, grew, fabricated and characterized AlGaInAs/GaInAs QWIPs suitable for operation at 3-5 μm, and 8-12 μm spectral range. We fabricated mid-wave IR 320 x 250 focal plane arrays, hybridized them with Si -readout circuits and performed radiometric and imaging tests. Excellent imaging results of the mid-wave IR focal plane arrays with an operability of 88% and mean NEDT of 0.09K have been achieved. To our knowledge, this is the first imaging with InP based QWIPs focal plane array.

Non-Geiger-mode single-photon counting APDs with high detection probability and afterpulse-free performance

We report high gain, high sensitivity 1064-1550 nm avalanche photodiodes (APDs) that are capable of single photon counting in the linear mode below the breakdown voltage and at room temperature. Epitaxial Technologies has developed AlInAs/GaInAs APDs with multiplication gains as high as 347,000, sensitivities of -69 to -77 dBm and photon detection efficiencies as high as 27%. The single photon counting APDs are free of afterpulse artifacts even for pulse widths in the nanosecond range. They can detect single photons at up to 139 MHz and have the capability for gigahertz repetition rate. Based on innovative and proprietary APD production technologies, the APDs have excess noise factors as low as 2 with the high gain. To our knowledge, these are the highest multiplication gains simultaneous with low excess noise factors and high sensitivities reported so far for long wavelength APDs.