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In this work, we have systematically investigated the technique of low-temperature AlN interlayer in MOCVD growth of double heterojunction high-electron-mobility transistors buffer stacks on 200 mm Si (111) substrates. We have demonstrated that a continuous compressive stress can be maintained by insertion of interlayers which compensated a large tensile stress during cooling for a thick buffer. This eventually led to a low wafer bow and a good surface quality that enabled wafers with full device stack meeting the specifications for processing in our 200 mm CMOS pilot line. We also demonstrated at both forward and reverse bias conditions a significantly improved vertical buffer breakdown voltage (which is defined at a leakage current of 1 µA/mm² in the present work) of >500 V at 25 °C and >300 V at 150 °C, respectively. [ABSTRACT FROM AUTHOR]

AlGaN/GaN/AlGaN double heterojunction high-electron-mobility transistors were grown on 200 mm Si (111) using metalorganic chemical vapor deposition. The Al composition of AlGaN barrier varied from 20 at% to 30 at% and thickness from 10 nm to 20 nm. In some structures, a 1 nm AlN interlayer was inserted between AlGaN barrier and GaN channel. The as-grown wafers were proven to be of high material quality and the layer thickness were well controlled to the target values. A buffer break down voltage of over 700 V were obtained for all grown wafers. Compared to their counterparts without AlN interlayer, structures with AlN interlayer showed a much lower and more uniform two-dimensional electron gas sheet resistance. With the presence of AlN interlayer, the sheet resistance was much less sensitive towards variations in AlGaN barrier composition and thickness. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

V-defects can be very detrimental to the functionality of GaN based light emitting diodes (LEDs) and high power transistors grown on 200 mm Si (111) substrates. This work focuses on reducing these detrimental defects in the GaN/AlGaN/AlN stacks grown in a Veeco Turbodisc Maxbright MOCVD system. The origins of V-defects in GaN/AlGaN/AlN material were studied by cross-sectional transmission electron microscope (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). It was found that V-defects were associated with inversion domain boundary (IDB) like defects, which started from the interface between the AlN nucleation layers and the Si (111) substrates. These IDB-like defects were terminated by generating V-defects in the upper layers. Encouraging the 2-D GaN growth mode helped to close these V-defects in the GaN layers, but relaxed the built-in compressive stress faster and resulted in excessive wafer bow. Optimizing the V/III ratio during the AlN nucleation step improved AlN crystal quality and surface morphology, and close V-defects in GaN without degrading wafers stress condition. [ABSTRACT FROM AUTHOR]