Picture of server farm and IT infrastructure

Where technology & law meet: Open Access research on data security & its regulation ...

Strathprints makes available Open Access scholarly outputs exploring both the technical aspects of computer security, but also the regulation of existing or emerging technologies. A research specialism of the Department of Computer & Information Sciences (CIS) is computer security. Researchers explore issues surrounding web intrusion detection techniques, malware characteristics, textual steganography and trusted systems. Digital forensics and cyber crime are also a focus.

Meanwhile, the School of Law and its Centre for Internet Law & Policy undertake studies on Internet governance. An important component of this work is consideration of privacy and data protection questions and the increasing focus on cybercrime and 'cyberterrorism'.

Explore the Open Access research by CIS on computer security or the School of Law's work on law, technology and regulation. Or explore all of Strathclyde's Open Access research...

Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode

Ajia, Idris. A. and Edwards, Paul R. and Pak, Yusin and Belekov, Ermek and Roldan, Manuel A. and Wei, Nini and Liu, Zhiqiang and Martin, Robert W. and Roqan, Iman S. (2018) Generated carrier dynamics in V-pit enhanced InGaN/GaN light emitting diode. ACS Photonics, 5 (3). pp. 820-826. ISSN 2330-4022

[img] Text (Ajia-etal-ACS-Photonics-2017-Generated-carrier-dynamics-in-V-pit-enhanced-InGaN-GaN-light-emitting-diode)
Ajia_etal_ACS_Photonics_2017_Generated_carrier_dynamics_in_V_pit_enhanced_InGaN_GaN_light_emitting_diode.pdf
Accepted Author Manuscript
Restricted to Repository staff only until 18 December 2018.

Download (1MB) | Request a copy from the Strathclyde author

Abstract

We investigate the effects of V-pits on the optical properties of a state-of-the art highly efficient, blue InGaN/GaN multi-quantum-well (MQW) light emitting diode (LED) with high internal quantum efficiency (IQE) of > 80%. The LED is structurally enhanced by incorporating pre-MQW InGaN strain relief layer with low InN content and patterned sapphire substrate. For comparison, a conventional (unenhanced) InGaN/GaN MQW LED (with IQE of 46%) grown under similar conditions was subjected to the same measurements. Scanning transmission electron microscopy (STEM) reveals the absence of V-pits in the unenhanced LED, whereas in the enhanced LED, V-pits with {10-11} facets, emerging from threading dislocations (TDs) were prominent. Cathodoluminescence mapping reveals the luminescence properties near the V-pits, showing that the formation of V-pit defects can encourage the growth of defect-neutralizing barriers around TD defect states. The diminished contribution of TDs in the MQWs allows indium-rich localization sites to act as efficient recombination centers. Photoluminescence and time-resolved spectroscopy measurements suggest that the V-pits play a significant role in the generated carrier rate and droop mechanism, showing that the quantum confined Stark effect is suppressed at low generated carrier density, after which the carrier dynamics and droop are governed by the carrier overflow effect.