The Growth of InGaN/(Al)GaN Quantum Well Structures in a Multi-Wafer High Speed Rotating Disk Reactor
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Internet Journal o f
Nitride S emiconductor Research
Volume 1, Article 24
The Growth of InGaN/(Al)GaN Quantum Well Structures in a Multi-Wafer High Speed Rotating Disk Reactor Alan G. Thompson , M. Schurman, Z. C. Feng, R. F. Karlicek, T. Salagaj, C. A. Tran, R. A. Stall EMCORE Corporation This article was received on June 2, 1996 and accepted on October 24, 1996.
Abstract . In the past year, several organizations have fabricated reliable, high-brightness LEDs from III-Nitride materials that emit in the blue and green. Recently, Nichia in Japan have announced lasing action in GaN-based diodes. Quantum well structures are key to all these results, offering higher brightness, narrower EL linewidths, and a wider spectral range. In order for the III-Nitride technology to develop, the material growth technique must offer high volume at low cost in addition to the requisite device performance. To date, only MOVPE has demonstrated this capability. We have previously reported the growth of GaN, InGaN, and AlGaN layers by MOVPE in a multi-wafer, high-speed rotating disk reactor. Both n- and p-doping and high quality optical properties have been achieved. In this paper we extend this earlier work and present results of the performance of InGaN / (Al)GaN quantum well structures. Intense PL spectra were observed in the violet and blue regions. The thinnest wells show evidence from PL and DCXRD measurments of either discontinuous layers (islands) or a diffuse upper interface, with preliminary TEM results showing the latter to be the most likely. We also report excellent uniformity of these quantum well structures, and show electroluminescence from a SQW diode emitting at 473 nm.
1. Introduction It is now widely recognized that the InGaAlN materials system can be applied to a number of technologically important optoelectronic and electronic devices [1], including LEDs emitting in the blue [2] and green [3], uv detectors [4], and high frequency /high temperature electronics [1] [5] [6]. The recent report [7] by Nakamura’s group at Nichia of the first laser diodes fabricated from these materials, generating light at the shortest wavelength reported to date for any semiconductor material, has generated enormous excitement. These laser diodes, and many other devices reported or proposed, rely on bandgap engineering to achieve electron, hole, and photon confinement. In particular, the use of quantum well (QW) effects extends the device designer’s options even further, and is necessary for thicker InGaN layers and higher In compositions to circumvent lattice parameter differences between adjacent layers. Indeed, the Nichia laser diode structure includes 26 periods of 2.5 / 5.0 nm QW / barrier in the active region [7]. It is therefore important to determine the conditions at which quantum wells can be grown, to fully realize the potential of this material system. In order for commercial development of III-Nitride technology to proceed, the material growth technique must offer high wafer volume at low unit cost, in addition to the
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