Introduction
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The poor matching between the III-nitride and sapphire in the lattice parameter and
thermal expansion coefficient brings a high density of threading dislocations(TDs).
•
It is well known that the V-defects formed during the MOCVD growth originate only
from the InGaN well layers, suggesting that V-defect formation is related to local In
segregation.
•
Though extensive research has been focused on the structural features and formation
mechanism of V-defects, however, there still exist some important problems, such as
how is the influence of V-defects on the electronic and optical properties of InGaNbased devices.
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Besides, not much attention has been put forward to build a connection between Vdefects and macroscopic parameters of the film, such as period number of QWs.
•
In this letter, we have investigated the dependence of V-defect formation, related
reverse leakage current, and electroluminescence(EL) efficiency of InGaN/GaN
MQW LEDs on the period number of QWs.
1
Experiments
Chip size
300 × 300 µm2
Ni/Au
5/5 nm
Periods of well
p- pad
150 nm
1040 ℃
Mg-doped p-GaN
4/38 nm
810/860 ℃
InGaN/GaN MQW
2 μm
1080 ℃
Si-doped n-GaN
n- pad
LED 1
3
LED 2
4
LED 3
5
Ti/Al/Ti//Au
150/250/50/150 nm
GaN buffer layer
c-plane sapphire
2