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ECE 443 Course Project Highlights: Efficient Micro LEDs, Innovations in Clean Power, and Solar Cell Development

5/26/2021

Joseph Park, Illinois ECE

ECE NANOFAB Cleanroom where ECE 443 students conducted their hands-on experiments.
ECE NANOFAB Cleanroom where ECE 443 students conducted their hands-on experiments.

Every spring, the ECE 443 LEDs and Solar Cells course encourages the class to address a grand societal challenge by putting the students’ semester-long learnings into the creation of a project. The objective of the class is to explore energy conversion devices so as to enable energy-efficient and scalable light emitting diodes and solar cells as solutions to the grand challenges in energy, communication, and health.

With support from Microlink Devices and Crosslight, the class thus competed for two distinct project competitions: MicroLink Devices Best Project Award and the Crosslight Best Project Award

The MicroLink Devices Best Project Award was given to senior Omar Kazi for his project entitled "Multi-Quantum Well (MQW) GaAs/AlGaAs Solar Cell." 

Solar photovoltaic technologies have garnered an increasing amount of attention due to their relevance to developing sustainable energy systems in the future which do not harm the environment. Multiquantum well (MQW) solar cells offer a potential device structure that can improve the current generation and efficiency of conventional p-i-n junction solar cells.

In Kazi's study, a single-junction MQW GaAs solar cell structure using 13 GaAs/Al0.35Ga0.65As quantum wells was proposed and simulated using Crosslight APSYS (TCAD software). The structure of the quantum well region is optimized by investigating the effects of the Al0.35Ga0.65As barrier thickness and the GaAs quantum well thickness on the device performance. The optimized cell efficiency was found to be 7.636% when 50 nm quantum wells and 1 nm barriers were used. This performance provided insights into how tunneling can reduce the performance of a MQW from its maximum theoretical efficiency and the trade-off between the thickness of the barriers and wells to design an optimal solar cell configuration.

The Crosslight Best Project Awards were given to graduate students Yu-Chieh Chiu and Jonah Messinger, a senior in the Engineering Physics Department pursuing a master's degree in Energy Systems and a minor in the Hoeft Technology and Management program. Chiu was recognized for his project entitled "Designing Efficient Micro Light Emitting Diodes for Display Applications." 

Demands for high performance displays have risen due to applications ultra-high-definition TV’s, mobile/wearable devices, AR/VR displays and more. Current display technology such as OLED and LCD have some limitations that prevent the best possible experience for uses. Micro light emitting diodes (LED) have become a strong contender in next-generation displays they have some advantages compared to LCD and OLED. Micro LED can achieve higher peak brightness, better color accuracy, faster response times and are more reliable; however one undesirable effect of scaling down LEDs for display applications is the decrease in efficiency.

Through TCAD simulation done in Crosslight APSYS, the scaled-down behavior of micro LEDs was investigated in this report to design efficient micro LEDs for display applications. With surface treatments, this effect could be reduced; when no surface non-radiative recombination is present, scaling does not decrease peak IQE, however, droop became more significant as the size of the LED is reduced. By optimizing its size and structural design, micro LEDs have shown to be a strong contender in next-generation display technologies

Messinger was recognized for his project entitled "Harnessing Cobalt-60 Gamma Radiation with ZnTe Gammavoltaic Devices and an LuI3 Scintillator Interface for Clean Firm Power Generation."

Utility-scale clean power generation is a crucial component to global energy decarbonization. Solar photovoltaic (PV) power is a key technology in this regard and produced ~3% of global electricity generation in 2019. However, solar power is a variable renewable electricity generation resource. Solar PV is fundamentally limited in capacity factor based on terrestrial solar illumination. Capacity factor is a metric that denotes the proportion of annual energy generation to the product of rated power multiplied by the total number of hours in a year. Messinger's study serves as a proof of concept for a gammavoltaic device to harness gamma radiation from cobalt-60 (Co-60). 

Crosslight’s TCAD software Advanced Physical Models of Semiconductor Devices (APSYS) application is used to simulate the photovoltaic cell performance under various doping and device thickness parameters yielding a maximum photovoltaic cell efficiency of 11.90%. The proposed gammavoltaic device simulation results in initial system efficiency of 3.14% and power output of 42,800 (W m-2 ) and decreases to a system efficiency of 0.98% and power output of 107 (W m-2 ) after 20 years of operation and no replenishment of the Co-60 gamma radiation source.

ECE 443 Best Projects can be found here.