High Quality Al-Ga-In-N Heterostructures Fabricated by MOVPE Growth in Multiwafer Reactors
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Internet Journal o f
Nitride S emiconductor Research
Volume 2, Article 9
High Quality Al-Ga-In-N Heterostructures Fabricated by MOVPE Growth in Multiwafer Reactors D. Schmitz, R. Beccard, O. Schoen, R. Niebuhr, B. Wachtendorf, Holger Juergensen AIXTRON GmbH This article was received on June 12, 1997 and accepted on July 7, 1997.
Abstract We present results on the growth of Al-Ga-In-N films in multiwafer reactors with 7x2" wafer capacity. The design of these reactors allows the combination of high efficiency (TMGa efficiency for GaN around 30%) and excellent uniformity. Results on the growth of all materials from the Al-Ga-In-Nitride family are presented in detail. GaN is grown with an excellent optical quality and very good thickness uniformity below 2% across 2" wafers. The material quality is shown by electron mobility of more than 500 cm2/Vs at an intentional Si-doping of approximately 1x1017 cm-3. Controlled acceptor doping with Mg yields carrier concentrations between 5x1016 and 1018 cm-3. The layer thickness uniformity of the films are better than 2% over a 2" wafer area. GaInN is grown with PL emission wavelengths in the visible blue region showing a uniformity better than 1.5 nm standard deviation. The film thickness uniformity represents the same figures as obtained for the binary. The compositional uniformity of AlGaN is in the sub 1% range corresponding to a wavelength variation below 1 nm. The fabrication of heterostructures from these binary and ternary materials is described as well as results from the characterization of these structures. The results show that reliable and efficient production of Al-Ga-In-Nitride based optoelectronic devices can be performed in multiwafer reactors.
1. Introduction Since GaN and it’s Al- and In-containing alloys were found to be the material of choice for short wavelength optoelectronics much work has been done to develop MOVPE processes. Within this the fabrication of high quality Al-Ga-In-N heterostructures for device applications is of special interest. After the introduction of the first commercially available nitride based blue LED by Nichia Chemical [1] the raising demand for blue and green Ultra-High-Brightness LEDs led to the development of MOVPE reactors for high throughputs. We designed MOVPE reactors with up to 7x2" wafers loading capacity for high temperature processes such as the GaN growth. The Planetary Reactor® is well adopted for high efficiency combined with an outstanding uniformity across the entire 2" wafer. Single layers as well as heterostructures were grown and investigated.
2. Experimental All growth experiments were carried our with an AIXTRON AIX2000HT Planetary Reactor® with a loading capacity of 7x2" wafers. This reactor offers fast heating and cooling rates due to its RF-coil heater and its water cooled reactor walls. In figure 1 a cross section of this reactor is shown while in figure 2 a photograph of the opened reactor is given. As sources we used TEGa, TMGa, TMIn, TMAl and NH3. P-type doping was achieved with DCp2Mg n-type dopin
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