Research website:  WBG Optronix Lab
Professor Shahedipour-Sandvik's research is focused on development of high performance wide bandgap III-Nitride optoelectronic materials and devices.  The focus of the research in the III-Nitride program is two fold:

1. Development of ultra low dislocation density AlInGaN layers with an emphasis on nanometer scale structures, homoepitaxial growth, and use of "truly compliant substrate" on Si substrate, the concept of which has been developed in our laboratory; understanding of role of defects in optical and electrical properties of the layers, and
2. Development of AlInGaN-based optoelectronic devices including UV-Visible detectors with ultra low leakage, UV and Visible LEDs for  solid state lighting and HFET structures for RF applications

The applications of devices based on this material system ranges from LEDs for solid state lighting (LEDs) to detectors for military (Space-to-space covert operation), civilian (air and water purification) and scientific (UV astronomy) applications to RF-power devices for communication.

In order to achieve high performance devices, Shahedipour-Sandvik's group has put in place an approach that focuses on developing high quality epitaxial layers though in depth characterization of their structural, optical and electrical signatures; developing device modeling capability to accommodate the desired characteristics and finally epitaxial deposition of the modeled structures and evaluation of their performance. This approach helps complete a loop that feeds information from one step of the study into the next and eventually development of high performance devices with known and predictable characteristics.

In our research we put heavy emphasis on the art of epitaxial growth of GaN-based layers and device structures using Metalorganic Chemical Vapor Deposition (MOCVD) system as well as their evaluation.

Select Publications

Selective area heteroepitaxy of nano-AlGaN UV excitation sources for bioflourescence application
V. Jindal, J. R. Grandusky, F. Shahedipour-Sandvik, S. F. LeBouef, J. Balch, and T. Tolliver
(submitted as part of the "Outstanding MRS Paper Award", J. Mater. Res. Sept. 2006)

High resolution x-ray diffraction analyses of ion-implanted GaN/AlN/Si heterostructures
R. J. Mayti, M. Jamil, F. Shahedipour-Sandvik
(submitted, 8th Biennial Conference on High Resolution X-Ray Diffraction and Imaging, 19-22 September 2006, Karlsruhe/Baden-Baden (Germany)

Identification of important growth parameters for the development of high quality Al>0.5GaN by MOCVD
J. R. Grandusky, M. Jamil, V. Jindal, N. Tripathi, F. Shahedipour-Sandvik
(submitted, J. Cryst. Growth, Aug. 2006)

Effect of strain on AlGaN hexagonal nanostructures by selective area heteroepitaxy
V. Jindal, J. R. Grandusky, N. Tripathi, F. Shahedipour-Sandvik
(submitted, Appl. Phys. Lett, Aug. 2006)

Mechanism of large area dislocation reduction
M. Jamil, J. R. Grandusky, v. Jindal, N. Tripathi, F. Shahedipour-Sandvik, (submitted, Phys. Rev. B, June 2006)

Ultrafast carrier dynamics and recombination in green emitting InGaN MQW LED
A. N. Cartwright, M. Cheung, F. Shahedipour-Sandvik, J. R. Grandusky, M. Jamil, V. Jindal, C. Wtzel, P. Li, T. Dtchprohm, and J. Nelson
Mat. Res. Soc. Proc. 916, 7 (2006)

Selective area heteroepitaxy of nano-AlGaN UV excitation sources for bioflourescence application
V. Jindal, J. R. Grandusky, F. Shahedipour-Sandvik, S. F. LeBouef, J. Balch, and T. Tolliver
Mater. Res. Soc. Proc. 916, 97 (2006)

Effect of HVPE GaN substrate condiction on the characteristics and performance of 405nm LEDs
J. R. Grandusky, M. Jamil, V. Jinal, F. Shahedipour-Sandvik, H. Lu, X._A. Cao, and E. B. Kaminsky
Mater. Res. Soc. Proc. 916, 91, (2006)

Development of pit-defect free smooth a-plane GaN surfaces on r-plane sapphire using MOCVD: A growth mechanism study
Vibhu Jindal, James Grandusky, Muhammad Jamil, Eric Irissou, Fatemeh Shahedipour-Sandvik, Kevin Matocha, Vinayak Tilak,
Phys. Stat. Sol. (a) 3, 179, (2006)

Reduction of crack and dislocation defects in GaN layers grown on Si substrate by MOCVD using a substrate engineering technique
M. Jamil, E. Irissou, J. R. Grandusky, V. Jindal, and F. Shahedipour-Sandvik,
Phys. Stat. Sol. (c) 3, 1787, (2006)

Development of native, single crystal AlN substrates for device applications
L. J. Schowalter, S. B. Schujman, W. Liu, M. Goorsky, M. C. Wood, J. Grandusky, and F. Shahedipour-Sandvik
Phys. Stat. Sol. (a) 203, 1667 (2006)

Origin of ring defects in high in content green InGaN/GaN MQW: An Ultrasonic Force Microscopy Study, F. Shahedipour-Sandvik, M. Jamil, K.Topol, J. R. Grandusky, K. A. Dunn, J. Ramer and V. N. Merai
Mat. Res. Soc. Inter. J. of Nitride Res. 10, 3 (2005)

Development of Strain Reduced GaN on Si(111) by Substrate Engineering
M. Jamil, J. R. Grandusky, V. Jindal, S. Guha, A. Arif, and F. Shahedipour-Sandvik
Appl. Phys. Lett. 87, 82103 (2005)

Optimization of the active region of InGaN/GaN 405 nm light emitting diodes using statistical design of experiments for determination of interaction effects
J. R. Grandusky, M. Jamil, J. A. Deluca, S. F. LeBoeuf, X. A. Cao, S. D. Arthur and F. Shahedipour-Sandvik
J. Vac. Sci. Tech. 23, B.1576 (2005)

Strain dependant facet stabiliziation in selective area heteroepitaxial growth of GaN nanostructures
F. Shahedipour-Sandvik, J. R. Grandusky, A. Alizadeh, C. Keimel, S. Taylor, S. LeBoeuf, S. Ganthi, and P. Sharma
Appl. Phys. Lett. 87, 233108 (2005)
Virtual Journal of Nanoscale Science & Technology, 12, 24 (2005)

Deep green emission at 570nm from InGaN/GaN MQW active region grown on bulk AlN substrate
F. Shahedipour-Sandvik, J. R. Grandusky, M. Jamil, V. Jindal, S. B. Schujman, L. J. Schowalter, R. Liu, F. A. Ponce, M. Cheung, A. Cartwright
SPIE Int. Soc. Ppt. Eng., 5941, 37 (2005)

Development of low dislocation and strain reduced GaN on Si(111) by substrate engineering
M. Jamil, J. R. Grandusky, V. Jindal, F. Shahedipour-Sandvik, S. Guha, M. Arif
SPIE Int. Soc. Opt. Eng.,5941 , 59411E (2005)

Important interaction effects in the growth of InGaN violet light emitting diodes by MOCVD
J. R. Grandusky, M. Jamil, V. Jindal, J. A. DeLuca, S. F. LeBoeuf, X. A. Cao, S. D. Arthur, F. Shahedipour-Sandvik
SPIE Int. Soc. Opt. Eng., 5941, 144 (2005)

Dislocation reduction and structural properties of GaN layers grown on N+implanted AlN/Si (111) substrates
M. Jamil, J. R. Grandusky, V. Jindal, N. Tripathi and F. Shahedipour-Sandvik
Mat. Res. Soc. Proc. 892, FF22-3.1 (2005)

Effects of GaN template annealing on the optical and morphological quality of the homoepitaxially overgrown GaN layer
James R. Grandusky, Vibhu Jindal, Muhammad Jamil and Fatemeh Shahedipour-Sandvik
Mat. Res. Soc. Proc. 892, FF27-7.1 (2005)

Patents