Intersubband Absorption at lambda ~ 2.1 mum in A-Plane GaN/AIN Multiple Quantum Wells

Intersubband optical absorption at lambda ~ 2.1 mum wavelength in doped 17.5 Angstrom GaN quantum wells (QWs) with 51 Angstrom wide intermediate AIN barriers is reported. A ~600 nm thick GaN template and 15 QWs have been grown by molecular beam epitaxy on R-plane sapphire substrate and display pure A-plane orientation. QWs with A-plane orientation are essentially free from spontaneous polarization, which is expected to greatly simplify the design of GaN/Al(Ga)N devices employing intersubband transitions.