Intersubband transition in (GaN)m/(AlN)n superlattices in the wavelength range from 1.08 to 1.61 μm

Intersubband transition (ISBT) in the wavelength range from 1.08 to 1.61 mum was systematically investigated in (GaN)(m)/(AlN)(n) superlattices (SLs), grown directly on (0001) sapphire substrates by rf-plasma molecular beam epitaxy. The SLs consisted of 90 periods of GaN wells (m=2similar to10 monolayers (ML) in thickness) and AlN barriers (nsimilar to11 ML). One ML corresponds to a thickness of around 2.6 Angstrom. For a 3.3 ML GaN well, the ISBT absorption wavelength reached a minimum of 1.08 mum, close to a theoretically predicted limitation, and it increased monotonically up to 1.61 mum with increasing well thickness to 9.5 ML. We observed absorption spectra as narrow as 61 and 66 meV in linewidth for 1.55 and 1.37 mum samples, respectively. (C) 2002 American Institute of Physics.