This program involves fundamental studies of the electronic properties of heterostructure electronic materials grown by metalorganic chemical vapor deposition (MOCVD), studies of devices made from these materials, and extension of these studies to integrated optical and electronic devices. Two specific areas of interest for this research are continued development of MOCVD-grown real-space transferred electron devices and other electronic devices, and development of multiterminal integrated laser structures, in which monolithic drive or modulation electronic devices are incorporated.

This program involves development of semiconductor lasers suitable for use in integrated optoelectronics. There are a number of key technical issues to be addressed in this program, including the development of etched facet structures, distributed feedback and distributed Bragg reflector grating structures, monolithic space division multiplexing arrays designed for fiber coupling, selective epitaxy for wavelength division multiplexing arrays and for multielement integration, master oscillator-power amplifier (MOPA) configurations, frequency stabilization, and distributed Bragg pulse shaper high-speed parallel-to-serial packet encoders.

We are investigating the growth and characterization of InGaAs-GaAs-AlGaAs nanostructures fabricated by selective-area metalorganic chemical vapor deposition (MOCVD) on GaAs substrates. Selective-area epitaxy utilizes growth inhibition by a silicon dioxide mask to enhance the growth rate in selected regions of a wafer. On a nanoscale, the growth rate difference between the (100) and (111) planes can be used to achieve reduction in the lateral dimension of the epitaxially grown material. Using this reduction, quantum wire dimensions can be achieved. The scientific objective of this program is to extend the technology of selective-area epitaxy by MOCVD to nano scale structures and to provide optical characterization of the structures to understand their microscopic nature.

The main goal of this program is to determine the feasibility of using ternary InGaAs substrates in the fabrication of optoelectronic devices, specifically semiconductor lasers. Initially, our efforts will focus on investigating the equality of deposited material on different compositions of InGaAs substrates. After epitaxial layers are characterized on these substrates, aluminum-free separate confinement laser structures (;gl ;sl 1-1.3 ;gmm) will be fabricated and tested.

There are several outstanding technical issues for narrowband systems, such as water vapor DIAL lidars, that must be resolved before solid-state laser-based remote-sensing systems have wide spread use. One issue is the development of cw local oscillators (LOs) based on semi conductor laser diode technology for use as injection seeders, which has not been fully realized because of the severe linewidth, tunability, and stability requirements of narrowband systems. This project will develop novel semiconductor devices specifically for use as tunable LO sources for narrowband water vapor DIAL systems operating in the 940 nm region. We will focus on a novel ridge-waveguide, distributed-Bragg-reflector laser which we believe has significant performance improvements for optical remote-sensing applications relative to conventional Fabry-Perot or distributed-feedback lasers.