Figures

Figure 1

Photoelectron spectra of Ga 3p, after surface treatments, labelled according to Table 1. Filled and open symbols are features associated with the positions of Ga 3p1/2 ,3/2 in pure Ga and in GaN [6], respectively.

Figure 2

Photoelectron spectra of the N 1s peak, after surface treatments see Table 1.

Figure 3

Photoelectron spectra of O 1s, after surface treatments see Table 1.

Figure 4

Photoelectron spectra of C 1s, after surface treatments see Table 1.

Figure 5

Changes in energy positions of Ga 3p and N 1s, measured relative to EF, as displayed in Figure 1 and 2. The energy position after the final surface treatment labelled (d) has been set to zero.

Figure 6

LEED patterns, (a) after the third NH3 flux anneal, the electron kinetic energy was 104 eV, (b) after the last surface cleaning consisting of Ga deposition during heating followed by NH3 flux anneal, the electron kinetic energy was 147 eV.

Figure 7

The Ga to N concentration ratio, after surface treatments see Table 1.

Figure 8

Fraction of ML of O to N +Ga and C to N +Ga, after surface treatments see Table 1.

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