Reduction of the bowing in MOVPE AlGaN/GaN HEMT structures by using an interlayer insertion method

Abstract

AlGaN/GaN high electron mobility transistor (HEMT) structures with reduced bowing were demonstrated using an interlayer insertion method. The InGaN interlayers had an effect of suppressing the epiwafer bowing up to 20 μm. By using InGaN/GaN multilayers as an interlayer, the epiwafer bowing was drastically decreased by up to 9.4 μm. The mobility of AlGaN/GaN HEMT structures with 10-period InGaN/GaN interlayers was 1083 cm2/Vs with the sheet carrier concentration, Ns, of 1.1 × 1013 at room temperature and 4997 cm2/Vs with Ns of 1.1 × 1013 cm2/Vs at 77 K. The FWHM of the X-ray rocking curve for (0004) reflection was 259 arcsec. The fabricated 2-μm-length and 15-μm-width high electron mobility transistor showed a high drain current (IDSmax = 617 mA/mm) and a high transconductance (gmmax = 174 mS/mm). The interlayer insertion method is effective for suppressing the epiwafer bowing. It may be a good solution for reducing the bowing of large-diameter epiwafers. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)