Senior Thesis Presentation
Friday, May 28, 2021 - 15:30 to 16:30
Event Speaker: 
YiPeng Teo
Local Contact: 

The study of carrier transport in light-emitting diode (LED) has been researched extensively in the past. However, most studies were implementing voltages above the turn-on voltage of the LED. Research on LEDs well below the turn-on voltage threshold is comparatively scarce for good reasons. When the supply voltage is below the turn-on threshold, the number of photons generated from carrier recombination within the semiconductor is exponentially suppressed. There also exists black body radiation from experimental background that would overwhelm the detection of LED emission. As a result, isolating an LED signal near zero-bias requires development of a new detection method. This paper aims to introduce the use of voltage modulation, thermal excitation of electrons, and the implementation of a lock-in amplifier to extract low magnitude signals produced by the LED. Results from low-bandgap LEDs near-zero voltage have shown a novel observation of different carrier and lattice temperature, hinting at the potential behind this method in measuring LEDs at an effectively off state. In addition, observations of a higher carrier temperature would provide significant motivation to further research and validate current carrier transport models.