Bandgap AlGaN

B OPTICAL BANDGAP AND LUMINESCENCE PROPERTIES OF AlGaN IN THE EXCITONIC REGION... 

In this formula, Eg, x and b are the optical bandgap, AIN molar fraction and bowing parameter, respectively. In order to determine this relationship, not only precise characterisation of Eg by the optical method but also precise determination of alloy composition x is quite important. The optical bandgap of AlGaN on sapphire in the whole compositional range was first reported by Yoshida et al [2] in 1982. They used optical absorption edge for determination of Eg, and x was determined by electron... 

TABLE 1 Summary of the bowing parameter of optical bandgap and excitonic bandgap of AlGaN reported to date. 

GaN/AlGaN heterostructures for solar-blind detectors have been grown by both RMBE and PMBE. By tuning the AIGaN bandgap the cut-off wavelength has been varied from 360 to 310 nm in p-i-n photovoltaic devices [72,73], Very competitive data were achieved, regarding the responsivity of 0.15 A/W and external quantum efficiencies of over 50%. 

The AlGaN alloys are suited to this application since they can be doped /7-t5q)e, have a larger bandgap, and are relatively well lattice-matched to ZnO. In this work, we present the results on optical and electrical properties of n-ZnO// -AlGaN heterojunctions. 

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