kuoching
Outline
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INTRODUCTION
DEVICE STRUCTURE AND FABRICATION
RESULTS AND DISCUSSION
CONCLUSION
REFERENCES
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INTRODUCTION
 It has recently been reported that this AlGaN EBL is insufficiently effective
for electron blocking due to the polarization induced band bending of both
the last quantum barrier (QB) and AlGaN EBL
 Besides this, the AlGaN EBL introduces an additional potential barrier that
impedes holes from spilling over into the MQW region
 Yet from an epitaxial point of view, it is difficult to grow these structures
with high crystalline quality.
 Kuo et al. numerically predicted the advantage of a step graded AlGaN
EBL with Al composition increasing towards the p-type layer.
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INTRODUCTION
 Zhang et al. demonstrated enhanced hole injection and internal quantum
efficiency by a step graded AlGaN EBL with gradually decreasing Al
content.
 In this letter, a taper-shaped multilayer AlGaN EBL (TEBL) was designed
and inserted in InGaN based LEDs.
 Experimental results show that the TEBL leads to improved electrical and
optical performance of InGaN LEDs including lower forward voltage,
enhanced efficiency, and mitigated efficiency Droop.
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