Properties of InGaN/GaN multiquantum wells grown on semipolar (20-21) substrates with different miscuts

• Differently angled surface regions have been prepared in (202¯1) GaN substrates.
• In the angled regions, GaN epitaxial layers have been grown and characterized.
• In the angled regions, InGaN multiquantum wells have been grown.
• Indium composition and emission wavelength have been measured in each region.
• Optical properties as a function of the region angle have been discussed.

We describe surface patterning as a method to obtain discrete regions of different local miscut angles, δ,   in semipolar (202¯1) GaN substrates. During patterning the region angle δ was varied between 0° and ±2° with respect to the growth plane. We chose two nonequivalent miscut directions: a   〈1¯21¯0〉 and c  ׳ 〈1¯014¯〉. On such patterned substrates InxGa1−xN/GaN quantum wells were grown by a Metalorganic Vapor Phase Epitaxy method. Angled regions were not planarized during growth and their initial miscut angles remained. We studied structural, morphological and optical properties of InxGa1−xN/GaN quantum wells as a function of δ. The intended In concentration, x  , was about 13% on exact oriented (202¯1) planes. For miscut towards the a-direction, indium content decreases and luminescence energy increases with δ. For miscut towards c׳, we observe quite different behaviors, indium content and quantum well width are constant and luminescence energy increases with δ. We propose the explanation of these effects on the basis of sample morphology, In-content and built-in electric field. The obtained results are important for understanding the role of miscut (intentional and unintentional) in basic properties of semipolar InGaN/GaN quantum well structures. It is also worth to note that, the spectral width of luminescence was the smallest for regions miscut 2° towards c׳ direction, which can be important for semipolar optoelectronic devices.