Depth dependent strain analysis in GaN‐based light emitting diodes using surface‐plasmon enhanced Raman spectroscopy

GaN‐based LEDs often develop unintended strain, due to the lattice and thermal expansion mismatch between the sapphire substrate and GaN layers. This residual compressive strain in GaN overlayers can cause a number of critical effects, such as wafer bowing, threading dislocation generation that impa...

Full description

Saved in:
Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2017-08, Vol.214 (8), p.n/a
Main Authors: Lim, Seung‐Young, Kim, Tae‐Soo, Jang, Bo‐Gyoung, Hong, Soon‐Ku, Song, Jung‐Hoon
Format: Article
Language:English
Subjects:
Bowing
Buffer layers
Compressive properties
Dislocations
Energy measurement
Excitation spectra
Gallium nitrides
GaN
gold
Light emitting diodes
Organic light emitting diodes
Position measurement
Quantum wells
Raman spectroscopy
Sapphire
Spectroscopic analysis
Spectrum analysis
strain
Strain analysis
Strain distribution
surface plasmons
Thermal expansion
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:GaN‐based LEDs often develop unintended strain, due to the lattice and thermal expansion mismatch between the sapphire substrate and GaN layers. This residual compressive strain in GaN overlayers can cause a number of critical effects, such as wafer bowing, threading dislocation generation that impact the overall properties of the epilayers, and the resulting device performance. Raman spectroscopy is known to be a useful technique for measuring strain analysis by monitoring the energy position of the E2 (high) mode. However, the local strain of a specific area cannot be obtained by conventional Raman spectroscopy since the excitation laser in the usual case is transparent and scattered throughout the whole LED structure. As a result, only the average strain of the entire structure is generally measured. We successfully analyzed the depth dependent strain distribution by applying the SERS technique and careful sample manupulation, to produce a truncated structure. Our results showed that the strain in the undoped GaN buffer layers and the n‐GaN layer gradually decreased up to the quantum well region, as the thickness increased, while the strain saturated in the active and p‐GaN layers. The depth depndent strain was also quantified using our analysis.
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.201600805