Near infrared absorption and room temperature photovoltaic response in AlN∕GaN superlattices grown by metal-organic vapor-phase epitaxy

We report on intersubband absorption of near infrared radiation in AlN∕GaN superlattice structures grown by metal-organic vapor-phase epitaxy. A good correlation between well thickness and absorption peak energy was obtained. One sample shows a photovoltaic signal which overlaps well with the corresponding absorption curve at around 1.5μm (830meV), a common wavelength in optical fiber telecommunication systems. This photovoltaic signal is strongest at temperatures around 75K and persists up to room temperature. The frequency response of this sample was measured with a modulated 1.5μm laser diode. The amplitude of the response was highest for a frequency of 36kHz.