GaN vertical and lateral polarity heterostructures on GaN substrates

• Published in: Journal of crystal growth Vol. 332; no. 1; pp. 43 - 47
• Main Authors: Hite, J.K., Bassim, N.D., Twigg, M.E., Mastro, M.A., Kub, F.J., Eddy, C.R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2011; Elsevier
• Subjects: A1. Polarity; A3. Metal organic chemical vapor deposition; Applied sciences; B1. Gallium nitride; B3. Lateral Polarity Heterostructures; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Devices; Electronics; Exact sciences and technology; Gallium nitrides; Imaging; Inversion layers; Inversions; Materials; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Polarity; Theory and models of film growth; Transmission electron microscopy; A1. Polarity; A3. Metal organic chemical vapor deposition; B1. Gallium nitride; B3. Lateral Polarity Heterostructures; Scanning electron microscopy; Epitaxial layers; Growth rate; Epitaxy; MOCVD; Gallium nitride; III-V compound; Surface states; Dislocation density; Interfaces; Transmission electron microscopy; Imaging; Growth mechanism; Polarity; Control method; Inversion layers; Heterostructures; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2011.08.002

A method to control local GaN polarity on GaN substrates without using Mg-induced inversion has been developed. This method rests on the development of thin alternative inversion layers and the use of the confined epitaxial growth technique to pattern and selectively grow the inversion layer. Used in conjunction with optimized subsequent GaN growth processes, the technique has resulted in structures demonstrating both vertical and lateral polarity inversion on GaN substrates. Scanning electron microscopy shows a smooth interface between regions of different polarities and a smooth surface, the result of equivalent growth rates for both polarities. Electron channeling contrast imaging is used to determine the dislocation density of each region. Transmission electron microscopy (TEM) images show full polarity conversion of the inverted layer. This process enables a wide range of novel variable polarity devices. ► Alternating GaN polarity material has been grown on N-polar GaN substrates. ► An inversion layer (IL) of thin AlN is patterned to selectively invert GaN polarity. ► Interface between polarities is vertical and laterally smooth. ► TEM confirms the IDB between polarities and complete polarity conversion over IL. ► ECCI shows difference in dislocation density between the two polarities.