Nitride Materials Device Fabrication and Characterization

Task Leader: Dr. David Starikov Dstarikov@space.svec.uh.edu

This task integrates the group's capabilities toward the realization of devices and systems that fall within the main objectives of the project. The focus is on the development of miniature visible-blind optoelectronic chemical sensors for process control and monitoring, field emission based cold cathodes for electron and ion sources working at pressures close to atmosphere, and high temperature electronics.

Visible-blind optoelectronic sensors

Wide band of GaN, AlN, InGaN, BN and CN semiconductor materials allow the development of Light Emitting Diodes (LEDs) with an optical spectra ranging from 250 nm to 1200 nm and Photo Detectors (PDs) that are insensitive to the visible light. The possibility to "tune" the band gap, and employment of various material combinations allow fabrication of spectrally matched optoelectronic pairs (LEDs and PDs) capable to detect species that interact with the UV light. This principle is employed in optoelectronic chemical sensors for process control and monitoring.

The combined use of Molecular Beam Epitaxy (MBE) and the high chemical and thermal strength of the III-V Nitride materials result in development of miniature and ruggedized MEMS-compatible chemical sensors for environmental, biomedical, industrial, military, and space applications.

Field emission devices

The main goal of this subtask is to develop and characterize nitride-based cold cathode materials for rugged electron and ion sources which operate with low power at pressures up to 0.1 Torr. Implementation of novel Nitride materials with negative electron affinity can further improve performance of cold cathode devices by enhancing the electron emission at lower operating voltage and improvement of the cathode material strength to low-vacuum and gaseous environments. We have already observed field emission with current densities close to 1 A/cm2 and turn-on at fields lower than 50 V/m from metallic and Si substrates coated with our Boron Nitride (BN) and Carbon Nitride (CN) films. Possibilities to employ the field emission of the nitride-based materials in MEMS-compatible pressure sensors is under investigation.

High temperature electronics

As a part of this subtask, development and characterization of alternative dielectric materials for the realization of high temperature electronic devices (diodes and transistors) is on the way. Boron nitride and gallium nitride thin films are well matched (thermal expansion coefficients and lattice structure) to Silicon Carbide (SiC) that is recognized as superior material for high temperature applications. The BN films are stable up to 1300°C and have the widest energy gap (6.4 eV) among IV and III-V materials. BN thermal conductivity is estimated to be close to 13 W/cmK and compares well with that of copper (4 W/cmK) and diamond (20 W/cmK).

As a result, our Metal Insulator Semiconductor (MIS) Schottky barrier structures based on GaN with interfacial BN layers maintain their rectification properties at temperatures up to 600 °C. The integration of such structures in three terminal electronic devices is the next step in the development of advanced III-V Nitride materials for high temperature electronics.


Space Vacuum Epitaxy Center
Web page created by Heidi Nussmeyer at hnussmey@bayou.uh.edu

Last modified: May 17, 1999