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The Al x Ga1 − x N/Al y Ga1 − y N multiple quantum well (MQW) structure for deep ultraviolet emission has been grown on sapphire by metal organic chemical vapor deposition (MOCVD). High resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and cathodoluminescence (CL) are used to characterize the structural and optical properties of MQWs, respectively. Clear step flows can be observed in the AFM image indicating a two-dimensional growth model. There are many cracks on the surface of the MQW structure because of the high tensile stress. HRXRD shows multiple satellite peaks to the 2nd order. The HRXRD simulation shows that the MQW period is about 11.5 nm. The emission peak of Al x Ga1 − x N/Al y Ga1 − y N MQWs is about 295 nm in the deep ultraviolet region from the CL spectra. [ABSTRACT FROM AUTHOR]

Al x Ga1- x N ternary alloys are very attractive materials for application to ultraviolet (UV) photodetection. In this work, high Al content Al x Ga1- x N films are grown on sapphire substrate by low pressure metalorganic chemical vapor deposition (MOCVD). The Al content in the Al x Ga1- x N epilayer is estimated to be 54% by high resolution X-ray diffraction (HRXRD) and Vegard’s law. The full width at half maximum (FWHM) of the rocking curve for the Al0.54Ga0.46N (0002) is about 597 arcsec. According to the transmittance measurement result, our sample is suitable for fabricating solar-blind photodetectors. The observed Fabry-Perot fringes in the transmission region indicate that high optical quality is obtained. Solarblind metal-semiconductor-metal (MSM) photodetectors based on the MOCVD-grown Al0.54Ga0.46N film are fabricated and tested. The detector has a low dark current of about 31 pA under a bias voltage of 5 V. An UV/visible contrast of about four orders of magnitude is observed and responsivity increases with increments of the bias voltage. [ABSTRACT FROM AUTHOR]