Photoluminescence of carbon in situ doped GaN grown by halide vapor phase epitaxy

Abstract

Carbon was in situ doped into GaN during halide vapor phase epitaxy and photoluminescence properties of the C-doped GaN film were investigated. It has been found that incorporation of carbon into GaN produces a significant yellow luminescence around 2.2 eV. The peak position of the yellow band blueshifts linearly and the intensity of that band monotonically decreases with measurement temperature, with systematic changes in the linewidth. These results suggest that multiple donor-acceptor recombination channels are involved in the yellow luminescence. © 1998 American Institute of Physics. ͓S0003-6951͑98͒02013-0͔Recent advances in GaN-based materials, 1 such as lightemitting diodes ͑LEDs͒, 2 have stimulated worldwide interest in developing novel GaN-based optoelectronic and electronic devices. Although a GaN continuous-wave ͑cw͒ injection laser diode has successfully been operated at room temperature with a lifetime greater than 1000 h, 3 some persistent problems in GaN material have to be resolved in order to realize higher performance devices. One such problem is the behavior and impact of carbon impurities in GaN. Carbon is one of the most common contaminants in the metalorganic vapor phase epitaxy ͑MOVPE͒ of GaN. 4 Carbon impurities in GaN are thought to occupy anion sites and act as acceptors. 5,6 Carbon may also combine with other defects, such as Ga vacancies, 7 due to the electronegativity and size differences between the carbon impurity and host atom. Carbon impurities are also believed to be related to yellow luminescence ͑YL͒ in GaN.7-10 Some of the initial photoluminescence ͑PL͒ studies on C-doped GaN were carried out by Pankove and Hutchby.7 They reported that C-implanted GaN exhibited a strong yellow luminescence band centered around 2.17 eV at 78 K. This band was attributed to defects arising from implantation damage, since the YL band could also be seen in samples implanted with other elements.7 Ogino and Aoki 8 found that the YL in both GaN microcrystal powder and needlelike crystals was greatly enhanced by intentional introduction of carbon into those materials. They concluded that the carbon impurities were crucial for YL. The YL was suggested to involve a radiative transition between a shallow donor, with the ionization energy of ϳ25 meV, and a deep acceptor, situated 860 meV above the top of the valence band. 8 Polyakov et al. 9 and Niebuhr et al. 10 have also attributed the observed YL in GaN grown by MOVPE to carbon impurities. The halide vapor phase epitaxy ͑HVPE͒ technique does not use carbon containing source materials but only uses NH 3 , HCl, and ultrapure Ga to synthesize GaN. 11,12 Carbon would only appear in these materials as an unintentional dopant. The YL band in typical HVPE-grown GaN is either absent or very weak 11,12 in agreement with the lack of carbon in the growth system. HVPE-grown GaN is therefore a suitable technique to study the correlation between YL and C atoms in GaN by intentional C doping during GaN growth. In this letter, we will report on the PL properties ...

Precursors for carbon doping of GaN in chemical vapor deposition

“…[16][17][18] However, due to the low reactivity of methane-caused by the highly symmetric geometry of the molecule-it often needs to be decomposed by, for instance, a plasma in the MBE reactor. Other dopants reported for MBE, halide vapor phase epitaxy, or metal organic vapor phase epitaxy are tetrabromomethane (CBr 4 ), 19,20 acetylene (C 2 H 2 ), 21 propane (C 3 H 8 ), 22 hydrogen cyanide (HCN), 23 carbon disulfide (CS 2 ), and carbon tetrachloride (CCl 4 ). 24 However, no thorough comparative investigation of carbon doping efficiency in GaN using different hydrocarbons has been published.…”

Selective excitation of the yellow and blue luminescence in n- and p-doped Gallium Nitride

“…The energy shifts between emission and excitation for those The temperature dependence of the selectively excited YL peaks was also measured, and the results for the second bulk sample are presented in Figure 2-6. The thermal quenching for temperatures above ~ 150 K is in contrast to YL excited above the band-gap, where only a small dependence on temperature in this range has been seen [68,90]. A significant broadening of peaks A, B, and C, also occurred as the temperature increased, so that the narrowed structures are difficult to discern at room temperature.…”

Selective excitation of the yellow luminescence of GaN

“…This is shown in Figure 2 The selectively-excited YL differs markedly from the E i > E g excited YL in its temperature dependence. One distinctive feature of the E i > E g YL noted in previous publications has been its lack of a dependence on temperature [10,18]. Figure 3 shows the selectively-excited YL spectra (E i = 2.471 eV) of a bulk sample measured for several temperatures (T) plotted on the same intensity scale.…”