Gallium photoluminescence measurement

Electron spin resonance reveals the unpaired electrons associated with impurities or structural defects and can be used to identify the lattice site positions of these features. Nitrogen is shown to substitute for carbon and acts as a shallow donor. The various ESR triplets due to nitrogen in several SiC polytypes give information on the lattice sites occupied. For the acceptor boron, ESR shows it to occupy Si sites only, in disagreement with DAP photoluminescence measurements which show only boron on carbon sites. It may be that boron substitutes on both sites and the two techniques have sensitivity for only one particular lattice site. The aluminium acceptor is not observed in ESR but gallium has been noted in one report. Transition metals, Ti and V, have been identified by ESR both isolated on Si sites and in Ti-N complexes. Several charged vacancy defects have been assigned from ESR spectra in irradiated samples. 

Figure 3.10 Photoluminescence measurement of gallium oxonitride in comparison to two...

The ionisation energies of the electronically active impurities have been determined primarily by photoluminescence techniques and Hall measurements. Ionisation energy levels of such impurities as nitrogen and some of the group III elements (aluminium, gallium, boron) in 3C-, 4H-, 6H- and 15R-SiC polytypes are compiled in TABLE 2. Nitrogen gives relatively shallow donor levels. In contrast, other p-type dopants have deep-level acceptor states. 

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