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Gold awards for 2016 Nanyang Research Symposium

Two of our science research students achieved Gold awards at the 2016 Nanyang Research Symposium. Their respective projects are detailed below:

Austin Goh Junzhen (CTG 203)

Project title: Temperature Based Schottky-Contact Leakage Current Studies in GaN HEMTs

Name & designation of NRP supervisor: Assoc Prof Ng Geok Ing, Associate Professor, School of Electrical & Electronic Engineering, College of Engineering
YJC teacher mentor: Mr Lee Kang Hao

Brief synopsis of the research project:
The schottky-contact gate leakage current in AlGaN/GaN high electron mobility transistors (HEMTs) is studied through temperature-dependent current-voltage from 225K to 400K. In order to understand the gate leakage mechanisms, GaN diodes with similar current-voltage characteristics as GaN HEMTs are used. The ideality factor and barrier height determined using the thermionic emission theory are found to be affected by temperature which is elucidated by the findings obtained from the GaN diode. It is observed that the current flow at lower temperatures can be attributed to other leakage mechanisms, while thermionic emission grows in proportion with the increase in temperature.

Pua Heng Yi (CTG 208)

Project title : Optimisation of VO2 thin films (hydrogel) to be used in Smart Windows

Name & designation of NRP supervisor: Dr Long Yi, Senior Lecturer, School of Material Science & Engineering, College of Engineering
YJC teacher mentor: Mdm Tay Woon Ping

Brief synopsis of the research project:
The world has been undergoing climate change for many years largely caused by high levels of energy consumption. The demand for high levels of energy has caused more fossil fuels to be burnt which resulted in the release of large amounts of carbon dioxide. Carbon dioxide, a known green house gas, traps heat and warms up the earth’s atmosphere. Singapore, ranked 12th in the world’s carbon footprint survey,  is actively trying to source for ways to reduce energy consumption. Most windows in Singapore are transparent, allowing sunlight to pass through resulting in the indoor temperature to rise and the need to use air-conditioning. Smart windows made of thermochromic materials decrease the amount of heat while keeping high illumination indoors. A composite material made up of VO2 and hydrogel, blocks infrared and visible light. Windows glazed with the composite material absorb lower solar energy, decreasing indoor temperature. Thus, energy used to power air conditioners is conserved. Tungsten doping is recommended to reduce the composite material’s high phase transition temperature, in order for it to be used in Singapore. This investigation reviewed one of the processes to create an optimum hydrogel by comparing and analysing different thicknesses of hydrogel , volumes of VO2  to coat the glass with and types of hydrogel to achieve the optimum amount of solar energy passing through a window while reflecting heat-generating waves. This minimises the use of electricity to cool down the room and yet provide enough light during daytime.  It was concluded from the findings that 9μl 75μm tungsten doped VO2 hydrogel has the best results, with an average Tlum of 56.6%, ∆Tsol of 15.0% and ∆TIR of 16.0%.

Congratulations and well done, Austin and Heng Yi!