Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

摘要

We demonstrate THz intersubband absorption (15.6-26.1 meV) in m-planeAlGaN/GaN quantum wells. We find a trend of decreasing peak energy withincreasing quantum well width, in agreement with theoretical expectations.However, a blue-shift of the transition energy of up to 14 meV was observedrelative to the calculated values. This blue-shift is shown to decrease withdecreasing charge density and is therefore attributed to many-body effects.Furthermore, a ~40% reduction in the linewidth (from roughly 8 to 5 meV) wasobtained by reducing the total sheet density and inserting undoped AlGaN layersthat separate the wavefunctions from the ionized impurities in the barriers.