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 1.5 mu m (830 meV), a common wavelength in optical fiber telecommunication systems. This photovoltaic signal is strongest at temperatures around 75 K and persists up to room temperature. The frequency response of this sample was measured with a modulated 1.5 mu m laser diode. The amplitude of the response was highest for a frequency of 36 kHz.