Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias
Abstract
:1. Introduction
- Carrier pairs are generated both thermally and through photogeneration.
- Carrier pairs recombine and emit photons.
- The energy of the emitted photons is a result of Fermi-Dirac statistics for the particular material, and is not inherently the same as Black Body.
- As long as there are carriers present, photo-recombination does not stop, even though carrier density is below intrinsic.
2. Materials and Methods
2.1. Approach of Experiment
2.2. Equipment Setup
- Placed the LED Box into target enclosure.
- Set the Signal generator to 40 Hz.
- Placed the LED Box in fluorometer.
- Set LED bias to values in the range of 0.60 V to −1.0 V.
- Manually adjusted the LED Box to maximize signal as measured by Lock-In Amplifier. Lock-in phase was set at this time.
2.3. Test Run Controls and Measurements
3. Results
3.1. Measured LED Intensity vs. Bias
3.2. Spectrum Measurements
3.3. Possible Sources of Errors in the Measurements
4. Discussion
4.1. Interpretations, Conclusions, and Expectations
- ○
- The semi-log plot of data shows straight line (within reasonable experimental error) through data points of intensity vs. LED bias voltage.
- ○
- Results are consistent with for shape of Ideal Diode, which adds weight to the validity of the experimental methods.
- ○
- The LED continues to have photo-recombination emissions at and below zero bias.
- ○
- As bias goes yet more negative, the intensity level would fall below the sensitivity of the fluorometer, so that our measurements would be dominated by noise (scattering from the straight line).
- ○
- As bias goes higher than applied, non-exponential behavior of the LED (Auger recombination and eventually failure) would be seen, so the semi-log plot would no longer be linear.
4.2. Analysis of Properties of Recombination
4.2.1. Electron Activity around the N-Type Heterojunction
4.2.2. Analysis of Measured Results
4.3. Next Steps
4.4. Summary
Supplementary Materials
Author Contributions
Funding
Conflicts of Interest
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Bias Voltage | Intensity Reading (a.u.) | |
---|---|---|
mV | Low | High |
260 | 133 | 133 |
288 | 242 | 242 |
212 | 39.5 | 39.5 |
168 | 11.7 | 12 |
112 | 3.5 | 3.7 |
64 | 1.0 | 1.2 |
14 | 0.21 | 0.48 |
3 | 0.25 | 0.32 |
−8 | 0.165 | 0.25 |
−18 | 0.125 | 0.21 |
−28 | 0.095 | 0.208 |
−36 | 0.068 | 0.145 |
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Orem, P.M.; Vogt, K.T.; Graham, M.W.; Orem, F.M. Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias. Electronics 2018, 7, 360. https://doi.org/10.3390/electronics7120360
Orem PM, Vogt KT, Graham MW, Orem FM. Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias. Electronics. 2018; 7(12):360. https://doi.org/10.3390/electronics7120360
Chicago/Turabian StyleOrem, Peter M., Kyle T. Vogt, Matt W. Graham, and Frank M. Orem. 2018. "Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias" Electronics 7, no. 12: 360. https://doi.org/10.3390/electronics7120360
APA StyleOrem, P. M., Vogt, K. T., Graham, M. W., & Orem, F. M. (2018). Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias. Electronics, 7(12), 360. https://doi.org/10.3390/electronics7120360