Paper EM-ThA9
ENABLE-Based Growth of In-Rich InGaN for Photovoltaic and Light-Emitting-Diode Devices
Thursday, November 12, 2009, 4:40 pm, Room B1
| Session: |
Quantum Structures and Nitrides Devices |
| Presenter: |
T.L. Williamson, Los Alamos National Laboratory |
| Authors: |
T.L. Williamson, Los Alamos National Laboratory
M.A. Hoffbauer, Los Alamos National Laboratory
K.M. Yu, Lawrence Berkeley National Lab
L.A. Reichertz, Lawrence Berkeley National Lab
N. Miller, Lawrence Berkeley National Lab
J.W. Ager, Lawrence Berkeley National Lab
W. Walukiewicz, Lawrence Berkeley National Lab
|
| Correspondent: |
Click to Email |
A wide range of photovoltaic (PV) and light-emitting-diode (LED) devices can be made utilizing the wide band gap tunability of InxGa1-xN (0.7 eV to 3.4 eV, 1>x>0). Growing In-rich InxGa1-xN films with strong photoluminescence in the green and red portions of the visible spectrum has faced considerable challenges due to In segregation and other materials issues. These challenges have precluded the growth of both compositionally graded InxGa1-xN materials and higher bandgap Ga-rich materials on top of lower bandgap In-rich materials. Overcoming these difficulties has proved formidable for conventional epitaxial techniques due to the low decomposition temperatures of In-rich materials (e.g. InN~550°C) and the required growth temperatures for Ga-rich materials (e.g. GaN >800°C).
Energetic neutral atom beam lithography & epitaxy (ENABLE) is a recently developed low-temperature thin film growth technology developed at LANL that utilizes a collimated beam of energetic neutral N atoms (kinetic energies 0.5 to 5.0 eV) to react with evaporated Ga and In metals to grow InxGa1-xN. ENABLE is similar to MBE, but provides a much larger N atom flux. The high kinetic energy of the reactive N atoms substantially reduces the need for high substrate temperatures, making isothermal growth over the entire InxGa1-xN alloy composition range possible at rates of >3 mm/hr with no toxic precursors or waste products.
Current progress using ENABLE for growing InN, GaN, InxGa1-xN, and graded InxGa1-xN films over the full composition range will be presented including data on film photoluminescence, crystallinity, electrical properties, doping, and electroluminescence. ENABLE-grown InxGa1-xN films show strong photo- and electro-luminescence spanning the entire visible region of the spectrum, with carrier mobilities ranging from ~10 to >1400 cm2/Vsec and background carrier concentrations typically in the low 1017 range. Evidence for p-type doping of In-rich InxGa1-xN films and characterization of p/n junctions will be discussed along with the prospects for using ENABLE to fabricate efficient devices for PV and LED applications.