  We report the influence of the In mole fraction on the material and
electrical characteristics of p-i-n InxGa1-xN homojunctions (x = 0.10-0.40)
synthesized by plasma-assisted molecular-beam epitaxy on GaN-on-sapphire
substrates. Junctions terminated with p-InGaN present improved carrier
extraction efficiency in comparison with devices capped with p-GaN, due to the
deleterious effect of polarization discontinuities on the device performance.
We demonstrate that the presence of Mg does not perturb the In incorporation in
InGaN, and it leads to a significant reduction of the stacking fault density.
p-In0.3Ga0.7N layers with a hole concentration of 3.2x1018 cm-3 are
demonstrated. InGaN homojunction devices show a peak EQE = 14+-2% in the
blue-to-orange spectral region, and an extended cutoff to 600 nm.
