Shallow–Deep InGaN Multiple-Quantum-Well System 
for Dual-Wavelength Emission Grown on Semipolar 
($$ 11\bar{2}2 $$) Facet GaN
We report growth and characterization of a shallow–deep InGaN/GaN multiple-quantum-well (MQW) system for dual-wavelength emission grown on semipolar ($$ 11\bar{2}2 $$) facet GaN. Structural and optical properties of the InGaN multiple-quantum-well system were investigated by scanning electron microscopy (SEM), cross-sectional scanning transmission electron microscopy (XSTEM), photoluminescence (PL), photoluminescence excitation (PLE), and time-resolved photoluminescence (TRPL) measurements. Cross-sectional transmission electron microscopy (XTEM) revealed that the growth rate of the InGaN well layers on the (0001) flat top microfacet (~500 nm) was about six times as fast as on the ($$ 11\bar{2}2 $$) inclined facet, whereas the growth rate of GaN barrier layers on the (0001) flat top facet was roughly 4.5 times as large as that on the ($$ 11\bar{2}2 $$) facet. A room-temperature PL spectrum showed dual-wavelength light emission of the shallow–deep InGaN multiple-quantum-well system situated at 2.720 eV (455 nm) and 2.967 eV (418 nm). The Stokes shifts between the two PL peaks and the two “effective bandgaps” were ~260 meV in energy for the deep quantum wells and ~233 meV for the shallow quantum wells. The TRPL decay demonstrated the short radiative recombination lifetime on the order of several nanoseconds in the InGaN MQW system. Realization of the shallow–deep InGaN multiple-quantum-well system with emission wavelength controllability would be useful to achieve III-nitride-based multicolor light-emitting devices for displays.