Intersubband absorption at lambda similar to 2.1 mu m in A-plane GaN/AlN multiple quantum wells

Intersubband optical absorption at lambdasimilar to2.1 mum wavelength in doped 17.5 Angstrom wide GaN quantum wells (QWs) with 51 Angstrom wide intermediate AlN barriers is reported. A similar to600 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 polarisation, which is expected to greatly simplify the design of GaN/Al(Ga)N devices employing intersubband transitions.