Experimental method

Eg (eV)

X-ray photoemission spectra

3.6 [a], 3.85 [b]

Optical and UV absorption

3.9 [c], 4.3 [d]

Laser-induced fluorescence (LIF)

4.02 [e]

Optical reflectivity spectra

4.5 [f], 5.2 [g]

Luminescence optical spectra

>5.5 [h], 5.89 [i], 5.95 [j]

Photoconductivity, and absorption spectra

5.8 [k], 5.83 [l]

Temperature dependence of electrical resistivity

7.1 [m]