Kean Boon Lee

  • Citations Per Year
Learn More
Electron mobility of AlGaN/GaN HEMTs is studied using a gate admittance-based technique. This analysis extends to electron densities as low as 4&#x00D7;10<sup>10</sup> cm<sup>-2</sup> with good accuracy. Zero lateral electric field is applied, in contrast to conventional methods. At these low electron densities, the mobility can be a factor of ~50 less than(More)
All-GaN-integrated cascode heterojunction field effect transistors were designed and fabricated for power switching applications. A threshold voltage of &#x002B;2 V was achieved using a fluorine treatment and a metal&#x2013;insulator&#x2013;semiconductor gate structure on the enhancement mode part. The cascode device exhibited an output current of(More)
The use of chemical vapor deposition diamond as a substrate for gallium nitride (GaN) to form GaN- on-diamond has the potential to allow for higher linear power densities in GaN high electron mobility transistors (HEMTs). The increase in GaN HEMT power density on diamond has been limited to date by the electrical leakage in GaN-on-diamond substrates. In(More)
The cascode combination of transistors is a simple and interesting way of turning a normally-on device into a normally-off one. Cascodes are usually used with wide bandgap materials such as gallium nitride (GaN) and silicon carbide (SiC) in which a wide bandgap normally-on device is connected to a silicon MOSFET. Integration of the different transistors to(More)
Dispersion in capacitance and conductance measurements in AlGaN/GaN high-electron mobility transistors is typically interpreted as resulting from interface states. Measurements on varying gate-length devices and a model of an interface-trap-free device are used to demonstrate that the distributed-resistance-induced dispersion is significant for 1-MHz(More)
Charge trapping and transport in the carbon doped GaN buffer of an AlGaN/GaN-on-Si high electron mobility transistor (HEMT) have been investigated. Back-gating and dynamic Ron experiments show that a high vertical leakage current results in significant long-term negative charge trapping in the buffer leading to current collapse under standard device(More)
2-D simulation of AlGaN/GaN HEMTs was carried out in order to investigate the mechanism of short-channel effect in highly scaled transistors. We demonstrate the impact of varying the barrier thickness as well as the gate lengths and show that high aspect ratio (gate length to barrier thickness) larger than 10 can effectively mitigate the short channel(More)
In this work, the temperature dependent TCAD and SPICE modeling platform of AlGaN/GaN HEMTs has been established by using Sentaurus TCAD and Silvaco UTMOST IV. Typically, the temperature co-efficient of series resistance, trans-conductance, sub-threshold swing and gate/buffer leakage has been extracted from the TCAD simulation. Based on that, the compact(More)
A small protein, NP-PI-II, with an N terminus identical to a part of a NJcotiana alata proteinase inhibitor (PI) II, and an inhibitory activity towards trypsin, has been isolated from flowers of Nicotiana plumbaginifolia. A larger protein was also present from which the smaller protein is likely derived. In N. plumbaginifolia the inhibitor is expressed at(More)