Nitride Semiconductors for Ultraviolet Detection.
Abstract
Monocrystalline Al(x)Ga(1-x)N (0.05 < or = x < or = 0.70) thin films, void of oriented domain structures and low-angle boundaries and in the undoped, n-type Si doped (x < or =0.40) and p-ype Mg doped (x < or =0.13) states have been grown via OMVPE directly on 6H-SiC substrates. The surface morphologies were smooth; the FWHM of the DCXRC curves (0002 reflection) were as low as 186 arc sec for the undoped films. Values of the bandgap as a function of composition showed a negative bowing parameter. A new OMVPE system devoted to growth and doping of In(x)Ga(1-x)N alloys and related alloys and a new method for gas source MBE of III-N materials at increased deposition rates have been commissioned. Temperature-dependent PL measurements of undoped GaN films indicated emission from both free and bound excitons. The exciton binding energy to the neutral donor was approx.7 meV. Photoluminescence at 4.2 K on a GaN film with a thickness gradient of .5 mm revealed an energy shift in the band-edge peak, most likely due to strain effects. Photoluminescence of GaN for thickness below .8 mm revealed an increase in the donor-acceptor pair (DAP) emission intensity which is tentatively attributed to an increase in acceptor doping. The use of HCl solutions to clean the surfaces of GaN(0001) yields the lowest O and C concentrations. jg p2
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1995
- Accession Number
- ADA303265
Entities
People
- Robert F Davis
Organizations
- North Carolina State University