D. R. Myers

Stability of strained quantum-well field-effect transistor structures

Conditions for stability of strained-layer structures and their implications for device fabrication are examined. Structures which have exhibited the best performance to date are found to be thermodynamically metastable (or at best marginally stable) structures, which will restrict the processing steps permissible in the integration of these devices to form complex circuits.<<ETX>>

Surface-emitting laser-based smart pixels for two-dimensional optical logic and reconfigurable optical interconnections

A monolithic smart pixel technology based on the integration of two-dimensional arrays of cascadable optical switches, optical logic gates, and optical switching nodes consisting of vertical-cavity surface-emitting lasers and heterojunction phototransistors or photothyristors is described. Different combinations of these components perform optical switching, logic, routing, memory, and regeneration. Latching, nonlatching, and bistable switches with high optical gain and contrast are demonstrated, along with all the simple single-stage Boolean optical logic functions. A 2*2 optical bypass-exchange node and a reconfigurable, multistage, two-dimensional optical switching network architecture are also described. >

Useful design relationships for the engineering of thermodynamically stable strained‐layer structures

Recent studies have provided sufficient knowledge about the dominant failure mechanisms for lattice‐mismatched strained‐layer heterostuctures to permit the design of thermodynamically stable strained‐layer systems for device applications. We have developed procedures that summarize this knowledge for the working device designer, and apply these relationships to the design of ion‐implanted, strained‐layer, quantum‐well lasers.

Characterization of thin AlGaAs/InGaAs/GaAs quantum‐well structures bonded directly to SiO2/Si and glass substrates

Strained GaAs/InGaAs/AlGaAs quantum‐well structures grown on GaAs have been removed from their original substrates by a lift‐off process and bonded directly to glass or SiO2‐coated Si substrates. Both undoped and modulation‐doped structures have been characterized before and after transfer by Hall measurements, variable temperature x‐ray diffraction, and photoluminescence. The bonded structures retain the high quality of the as‐grown layers.

Be‐implantation doping of GaAsxP1−x/GaP strained‐layer superlattices

We present Hall‐effect measurements of the first localized p‐type doping in GaAsxP1−x /GaP strained‐layer superlattices achieved by implantation of 1×1015 cm−2, 75 kV 9Be+ followed by controlled‐atmosphere annealing at 825 °C for 10 min. The acceptor activation (∼15% at 300 K) and the mobilities in the p regions (∼20 cm2/Vs at 300 K) are consistent with the values expected for type‐converted GaP‐based alloys. Depth‐dependent structural characterization by ion channeling demonstrates that the superlattice structure survived the implantation and annealing without loss of layer strain. These results demonstrate that Be implantation can be applied to produce localized doping in a strained‐layer superlattice system and reflect favorably on the stability of strained‐layer superlattices under particle bombardment and thermal cycling.

The effects of ion‐implantation damage on the first‐order Raman spectra of GaP

We have analyzed the effects of ion‐implantation‐induced damage on the first‐order Raman spectra of GaP, and have correlated changes in the Raman spectra with direct measurements of implantation‐induced surface stresses. We find that, at low ion fluences, the effects of implantation damage are to produce point defects that remove free carriers from doped material and to produce stresses in the undamaged regions. In this regime, the stress‐induced shifts of the Raman lines can be predicted from the known elastic constants of undamaged GaP. At intermediate fluences, implantation damage alters the elastic properties of GaP so that the stress‐induced shifts of the Raman lines are less than those predicted from the properties of the undamaged crystal. At higher doses, implantation‐induced surface stresses exceed the elastic limit of the damaged material. This plastic deformation of the implanted surface is accompanied by a rapid broadening of the phonon lines in the first‐order Raman spectra.

Cascadable, latching photonic switch with high optical gain by the monolithic integration of a vertical-cavity surface-emitting laser and a pn-pn photothyristor

The authors report the first demonstration of a cascadable, photonic switch based on the monolithic integration of a multi-quantum-well vertical-cavity surface-emitting laser (VCSEL) and a latching pn-pn photothyristor grown by low-pressure metalorganic vapor-phase epitaxy (LP-MOCVD). The VCSEL and pn-pn photothyristor structures can be independently optimized for optical switching, logic, and memory functions. Optical switching with high gain (30000), high contrast (30 dB), low switching power (11 nW), and latching memory have been demonstrated. The integrated pn-pn/VCSEL switch not only represents a volatile optical memory, but also can be used to implement a new class of optical logic gates with latching logic outputs.<<ETX>>

Novel reflectance modulator employing an InGaAs/AlGaAs strained‐layer superlattice Fabry–Perot cavity with unstrained InGaAs/InAlAs mirrors

We present a novel approach to optoelectronic devices by combining mechanically stable strained and unstrained epitaxial multilayers. We illustrate our approach with an optical reflectance modulator based on an asymmetric Fabry–Perot resonator designed to operate near 1.06 μm. The resonator is grown on a mechanically relaxed buffer of In0.11Ga0.89As deposited on a GaAs substrate. For mirrors, quarter‐wave stacks of In0.11Ga0.89As and In0.1Al0.9As, lattice matched to the buffer, are used. The Fabry–Perot cavity consists of an In0.23Ga0.77As/Al0.35Ga0.65As strained‐layer superlattice whose planar lattice constant also matches the buffer. Our first device operates at 1.04–1.05 μm depending on lateral position across the wafer. The insertion loss at resonance is less than 2 db and a fractional modulation of over 60% has been achieved with a 4 V bias swing.

Depletion edge translation waveguide crossing optical switch

A waveguide crossing optical switch using the depletion edge translation concept is described. By using a single AlGaAs/GaAs material growth and ion implantation technology, an impedance discontinuity is formed at the intersection of two waveguides. Switching operation has been observed, and a high-speed, small-device-size, and high-extinction-ratio optical switch are expected.<<ETX>>

An ion-implanted Ga(AsP)/GaP strained-layer superlattice photodetector

We present the wavelength and spatially dependent photoresponse of the first ion-implanted strained-layer superlattice (SLS) photodiodes. Devices were formed by Be+ implantation of GaAs0.15P0.85/GaP SLSs followed by controlled-atmosphere annealing. Spatial response of the devices is uniform to within 3 percent when probed by a laser spot of 4.4 µm diam, while the wavelength-dependent photoresponse is characteristic of SLSs in this material system. Although not fully optimized, the devices exhibit uncoated peak external quantum efficiencies of 30 percent. These results demonstrate that ion-implanted SLSs can perform as useful detectors while retaining the desirable properties of the as-grown strained-layer superlattice.