Challenges and Breakthroughs in the Development of AlGaN-Based UVC Lasers
Location:356 Fitzpatrick Hall
Office: 226B Cushing Hall
Despite the rapid progress in III-nitride- based laser diodes, sub-300 nm UV semiconductors lasers have not been realized yet, mainly due to technical and scientific barriers arising from the lack of proper crystalline substrates and poor understanding of defect control in the wide band gap semiconductors. Al-rich AlGaN alloys are the building blocks for these deep UV optoelectronics devices and it has been demonstrated that the highest crystalline quality Al-rich AlGaN films are obtained on AlN single crystal substrates. In addition to low dislocation density, reduction in non-radiative centers and compensating point defect is required to achieve high internal quantum efficiency. Issues to be discussed are classified in two main categories: (1) growth, crystallography and surface morphology control and (2) identification and control of point defects. In addition to this, results on electrically-pump laser structures will be discussed, showing the very near possibility of the first ever demonstration of deep UV semiconductor lasers. Such devices will find direct and immediate uses in health care, bio-defense and other commercial and defense applications. The use of light sources in the deep UV will lead to detection systems of different chemical and biological aerosols, providing for detection of a variety of pollutant agents among other effluents, in addition to help in increasing the availability of clean potable water through efficient UV disinfection.
Dr. Ramon Collazo
North Carolina State University
Dr. Ramón Collazo is an Assistant Professor in the Department of Materials Science and Engineering (MSE) at North Carolina State University (NCSU), researching on the growth and characterization of wide band gap semiconductor thin films, especially nitrides, diamond and related compound semiconductors. He received his B.S. in Physics from the University of Puerto Rico, San Juan, and this Ph.D. in MSE at NCSU in 1998. Afterwards he joint the ‘Laboratory for Research on Wide Bandgap Materials,’ at NCSU as Post-doc, research assistant professor, and in 2011 as Assistant Professor at NC-State. At present, he is particularly involved in the fundamentals of controlling the polarity in III-nitrides – a critical step for developing lateral polarity homojunctions along with their application to the first lateral p/n junction. He also works on the development of AlN bulk single crystal substrates, their surface preparation, and the subsequent epitaxial thin film deposition for optoelectronics and power device applications. He was awarded the Facundo Bueso Medal for Physics. He has published 2 book chapters and over 135 research articles in refereed journals.