A GaInN/GaN/AlGaN photodetector structure

Structure of the layers.

Scheme of the structure

TEM image of the QW (made by J. Borysiuk)

The sample has been grown by Metal-Organic Chemical Vapour Deposition by P. Caban in Institute of Electronic Materials Technology (ITME), Warsaw, Poland

Interferences in the buffer layer.

The sample is very flat. So it is possible to observe nice interferences. Light is reflected from upper surface of the sample and from GaN/sapphire interface. The two beams are very well parallel so they interfere. From the interference pattern, we can determine width of the GaN layer (2.66 μm at the center).

Photograph of interferences made in white light.

Interferences in 532-nm, green light.

Absorption spectra of the sample.

Photoluminescence maps.

Measurements of photoluminescence give information about quality of GaN and GaInN layers. GaN-related peak is at 360 nm. Its intensity and wavelength are nearly constant on whole surface of the sample.

Photoluminescence spectrum. GaN-related peak is at 360 nm. Emission from GaInN QW is at 400 nm.

Map of intensity of the GaN peak.

Map of wavelength of the GaN peak.

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GaInN QW related peaks have wavelengths between 390 and 420 nm depending on a position on the sample. the wavelength of emission from QW depends upon width of the well. The broader well - the longer wavelength. The circular shapes on the maps are due to substrate rotation during growth of the sample.

(A) Photograph of the sample. (B) Map of intensity of the GaInN QW peak. (C) Map of wavelength of the GaInN QW peak.

Photoluminescence has been measured by A. Kos and K. P. Korona in Institute of Experimental Physics, Warsaw University, Warsaw, Poland