NSF Award
9960329
This Small Business Innovation Research Phase I project will develop growth of a new material, GaAsNSb, that is lattice-matched to GaAs and has a bandgap as low as 1 eV or smaller. After establishment of growth by metalorganic chemical vapor deposition, we will focus on using this material as the base layer in a heterojunction bipolar transistor (HBT). This low-bandgap base will permit low-voltage operation, while the lattice-match will allow strain-free operation for high reliability and ease of monolithic integration. Another important use of low-bandgap GaAsNSb will be for long-wavelength (1300 nm) laser diodes. GaAsNSb, with 3% nitrogen, 8% antimony, is exactly lattice-matched to GaAs and should have a bandgap of 1 eV; for an HBT. The high-bandgap emitter can then be GaAs, thus eliminating the problems often associated with AlGaAs or GaInP, which are typical emitter materials on GaAs HBTs. Phase I will concentrate on growing, doping, and characterizing GaAsNSb, including forming and testing GaAs-GaAsNSb diodes that simulate the base-emitter junction of an HBT. Growth and fabrication of complete HBT structures is beyond the scope of a Phase I for this previously unexplored material. Since this process is GaAs-based, it is totally compatible with our existing HBT technology. Phase II will include optimizing GaAsNSb growth and doping control, growth of GaAs-GaAsNSb heterojunctions, optimizing HBT design, and growing, fabricating, and testing HBT devices. Use of GaAsNSb in optoelectronic applications may also be explored.<br/><br/>The research will result in a new low-voltage heterojunction bipolar transistor for use in cellular telephones. Such HBTs will have improved reliability and efficiency over existing GaAs-based devices. The low-bandgap, lattice-matched material to be developed here also will have applicability to long-wavelength lasers and other optical devices.
