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Cite this article as: MRS Internet J. Semicond. Res. 4S1, G3.2 (1999) ABSTRACT Pendeo-epitaxy of individual GaN and AlGa, N films and single- and multi-layer heterostructures of these materials have been achieved on a columnar GaN seed layer using metallorganic vapor phase epitaxy. These structures have been characterized using

scanning electron microscopy and atomic force microscopy. The RMS roughness value of the grown side wall plane (1120) of these structures was 0.099 nm. INTRODUCTION Recent topics of focused research in the Ill-Nitride community have been the selective area growth coupled with lateral epitaxial overgrowth (LEO) and the application

of this tandem process route to reduce the dislocation density of GaN films by several orders of magnitude in the overgrown areas. A new form of selective and lateral growth,

namely 'pendeo (from the Latin: to hang or be suspended ) -epitaxy' has been recently pioneered in our group ' 3, to achieve large area growth of II-N films having a continuous low dislocation density over the entire surface. This process route is based on the growth

of GaN off a side wall and the ability to laterally overgrow a mask that has been employed to stop vertical propagation of line and planar defects. Additional details of this procedure and the initial results of this research have been reported previously 4. In this paper we report the growth via pendeo-epitaxy of layered thin film structures consisting of GaN and AIGa,_ N. The following sections describe the experimental procedure necessary to achieve layered structures by this technique in detail and discuss the results and conclusion of this study. EXPERIMENTAL PROCEDURE Layered structures containing GaN and AlGa, N have been grown on a 0.5 ýtm to 1.0 ýtm thick GaN seed layer grown on a high temperature, 100 nm thick AIN buffer layer previously deposited on a 6H-SiC(000 I) substrate. All layers were grown using a cold-wall, vertical pancake style, RF-inductively heated metalorganic vapor phase epitaxy (MOVPE) system. The AIN buffer layers and the hexagonal GaN seed layers were each grown within the susceptor temperature ranges of 1080°C- I1120°C and 980°C1020'C, respectively, at a total pressure of 45 Torr. Triethylaluminum (20-25jtmol/min), triethylgallium (23-29ltmol/min), and NH, (1.5 slm) precursors were used in combination G 3.2 Mat. Res. Soc. Symp. Proc. Vol. 537 © 1999 Materials Research Society

with a H, (3 slm) diluent. A 100 nm thick silicon nitride layer, employed as a growth mask for blocking the continued threading dislocations during the pendeo-epitaxial growth stage, was deposited using a plasma enhanced chemical vapor deposition (PECVD) system. A 150 nm layer of nickel was subsequently deposited as an etch mask and patterned in (1100) oriented stripes using standard photolithography techniques. Two different masks were used to produce (a) 211m wide stripes with a spacing of 3jtm, and (b) 3ýtm wide stripes with a spacing of 71am. An inductively coupled plasma (ICP) etching system was employed to achieve the