Intersubband transitions at atmospheric window in Al_xGa_(1-x)N/GaN multiple quantum wells grown on GaN/sapphire templates adopting AIN/GaN superlattices interlayer

摘要

Defects and strain control in Al_xGa_(1-x)N/GaN multiple quantum wells (MQWs) for intersubband transitions (ISBTs) at atmospheric window grown on GaN/sapphire templates by metal-organic chemical vapor deposition have been investigated adopting strain modulation technique using A1N/ GaN superlattices (SLs) interlayer. It is found that cracking in the MQWs can be effectively avoided adopting AIN/GaN SLs interlayer. It is demonstrated that AIN/GaN SLs interlayer acts as a flexible layer and relieves most of the tensile strain through buried microcracks in AIN/GaN SLs interlayer. The intersubband absorptions at 3.6-4.1 μm wavelength region have been observed on the crack-free Al_xGa_(1-x)N/GaN MQWs. Our results open up prospects to realize crack-free and high quality Al_xGa_(1-x)N/GaN MQWs on GaN/sapphire templates for ISBTs devices at 3-5 μm atmospheric window.