AVS 59th Annual International Symposium and Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM+TF+AS-ThA

Invited Paper EM+TF+AS-ThA1
AlN-based Technology for Deep UV and High-power Applications

Thursday, November 1, 2012, 2:00 pm, Room 14

Session: Growth and Characterization of Group III-Nitride Materials
Presenter: Z. Sitar, HexaTech, Inc. & North Carolina State University
Authors: Z. Sitar, HexaTech, Inc. & North Carolina State University
B. Moody, HexaTech, Inc.
S. Craft, HexaTech, Inc.
R. Schlesser, HexaTech, Inc.
R. Dalmau, HexaTech, Inc.
J. Xie, HexaTech, Inc.
S. Mita, HexaTech, Inc.
T. Rice, North Carolina State University
J. Tweedy, North Carolina State University
J. LeBeau, North Carolina State University
L. Hussey, North Carolina State University
R. Collazo, North Carolina State University
B. Gaddy, North Carolina State University
D. Irving, North Carolina State University
Correspondent: Click to Email
For the first time in history of III-nitrides, the availability of low defect density (<103 cm-2) native AlN substrates offers an opportunity for growth of AlGaN alloys and device layers that exhibit million-fold lower defect densities than the incumbent technologies and enable one to assess and control optical end electrical properties in absence of extended defects. Epi-ready AlN wafers are fabricated from AlN boules grown by physical vapor transport at temperatures between 2200 and 2300°C. Gradual crystal expansion is achieved through a scalable, iterative re-growth process in which the high crystal quality is maintained over many generations of boules. Despite the excellent crystal quality, below bandgap optical absorption bands in the blue/UV range affect the UV transparency of wafers. We use density functional theory (DFT) to develop a model to understand the interplay of point defects responsible for this absorption. We show a direct dependence of the mid-gap absorption band with the carbon concentration within the AlN. Low defect density AlN and AlGaN epitaxial films are grown upon these wafers that exhibit superior optical properties in terms of emission efficiency and line width and can be doped with an efficiency that is several orders of magnitude higher than possible in technologies using non-native substrates. UV LED structures and Schottky diodes were fabricated on these materials that exhibit low turn-on voltages and breakdown fields greater than 10 MV/cm. This presentation will review state-of-the-art of AlN-based technology and give examples of potential applications in future devices and contrast these with other wide bandgap technologies.