ON THE ORIGIN OF ELECTRICALLY ACTIVE DEFECTS IN ALGAN ALLOYS GROWN BYORGANOMETALLIC VAPOR-PHASE EPITAXY

Citation
Ay. Polyakov et al., ON THE ORIGIN OF ELECTRICALLY ACTIVE DEFECTS IN ALGAN ALLOYS GROWN BYORGANOMETALLIC VAPOR-PHASE EPITAXY, Journal of applied physics, 80(11), 1996, pp. 6349-6354
Citations number
27
Categorie Soggetti
Physics, Applied
Journal title
ISSN journal
00218979
Volume
80
Issue
11
Year of publication
1996
Pages
6349 - 6354
Database
ISI
SICI code
0021-8979(1996)80:11<6349:OTOOEA>2.0.ZU;2-Q
Abstract
Shallow and deep centers were studied by means of temperature dependen t Hall effect and photoluminescence (PL) measurements in two sets of u ndoped n-AlGaN samples grown by organometallic vapor phase epitaxy. Th e samples of these two series were grown under different conditions an d had, as a result, electron concentrations differing by several order s of magnitude. The composition dependence of ionization energies of d ominant donors in these two sets of samples is very different indicati ng that different types of centers are involved, but in both cases the y are most probably related to some native defects. These defects beha ve as hydrogen-like donors for low Al compositions and become increasi ngly deeper with increasing Al content. The shallow-deep transition oc curs at about x=0.2 in the low conductivity AlxGa1-xN series and at ab out x=0.5 for the high conductivity series. Several PL bands were dete cted in AlGaN and it is shown that the band at 3.05 eV is due to a rad iative transition between deep donors in the upper part of the band ga p and holes in the valence band or on shallow accepters. For the yello w luminescence band at 2.25 eV it is demonstrated that this band consi sts of two overlapping bands and that the dominant band is due to a tr ansition between the native donors and a carbon-related deep center. ( C) 1996 American Institute of Physics.