Date of Award
Open Access Dissertation
M. Asif Khan
III-Nitride based deep ultraviolet (UV) light emitting diodes (LEDs) are prospective candidates to replace the conventional bulky, expensive and environmentally harmful mercury lamp as new UV light sources, used in the applications of water and air purification, germicidal and biomedical instrumentation systems, etc. Due to the lack of native substrates and poor carrier injection, AlGaN-based deep UV LED is suffering from low optical power and low overall efficiency, which prevents the availability of low cost, high efficiency deep UV LED on the market.
This dissertation is focused on improving the efficiency of deep UV LEDs, by improving the base template epilayers, specifically silicon doped n-type AlGaN electron cladding layer on which the subsequent quantum well and other device layers are grown. Approaches such as short period superlattice (SPSL) nAlGaN and silicon modulation doping nAlGaN are shown to effectively decrease the threading dislocation density(TDD) from 1.2 x 109cm-2to 3×108cm-2, followed by the improvement of sheet resistance to 53 Ohm. The improvement of crystal defect density is believed to contribute to the increase of internal quantum efficiency (IQE) and thus the overall device efficiency. Deep UV LED on a wafer device employing proposed silicon doping modulation technique shows light emission peak at 281nm and yields 25% improvement of the optical power due to the dramatic reduction of the dislocation density as well as the overall efficiency.
CHEN, H.(2013). Dislocation Reduction In Silicon Doped High Aluminum Content Algan Layers For Deep UV Optoelectronic Devices. (Doctoral dissertation). Retrieved from http://scholarcommons.sc.edu/etd/2405