Project Title:

1.3 Micron for Laser Beams In(A1Ga)As Photovoltaic Laser Energy Converters

10.04-6000
900507
1.3 Micron for Laser Beams In(A1Ga)As Photovoltaic Laser Energy Converters

Abstract:

This project will investigate unique laser energy converters (LECs) for 1.315 micron
(0.943 eV) iodine laser, space power systems. The goal is to convert 40-50 percent
of the incident laser power of 500-1000 W/cm2 to electrical power. To achieve the
optimum 0.94 eV bandgap, metalorganic chemical vapor deposition (MOCVD) of an innovative
compound semiconductor, InO.53(A1xGa1-x)0.47As lattice-matched to InP substrates,
is planned. The bandgap of In0.53GA0.47As (0.75 eV) lattice-matched to InP is sub-optimal;
however, by adding A1 to the InGaAs so that the A1xGa1-x fraction stays at 0.47,
the lattice-match to InP is maintained while the epilayer bandgap increases. Initial
calculations indicate In0.53A10.13Ga0.34As has the optimum 0.94 eV bandgap. An innovative,
planar, series-connected, multijunction LEC should limit series resistance effects.
A planar approach avoids some of the processing problems inherent in vertical multijunction
designs. In Phase I, In0.53GA0.47As (control) and In0.53A10.13Ga0.34As prototype
layers will be grown on InP substrates with InP windows. The bandgaps will be checked
by photoluminescence, the lattice-match by X-ray diffractometry, and the doping by
CV profiling. Cells will be fabricated to check the pn junctions and to measure the
log IV, quantum efficiency, and power conversion efficiency. Planar, multijunction
LEC will be designed using measured data from the actual material, with particular
attention paid to attaining a low series resistance and high efficiency. In Phase
II, full-sized, optimized, planar, series-connected multijunction LECs based on the
Phase I work would be grown, fabricated, and tested.
A large market may occur in the sale of custom epilayers in the In0.53A1xGa1-xAs
system for lattice-matched, opto-electronic applications requiring bandgap engineering
from 0.8 to 1.4 eV, complementing the 1.4-to-2.3 eV range covered by the lattice-matched
A1xGa1-xAs/GaAs system.
indium, gallium, aluminum, arsenide, laser, power, converters, space