Abstract
Yellow luminescence (YL) of unintentionally doped GaN (u-GaN) peaking at about 2.2 eV has been investigated for decades, but its origin still remains controversial. In this study, ten u-GaN samples grown via metalorganic chemical vapor deposition (MOCVD) are investigated. It is observed from the room temperature (RT) photoluminescence (PL) measurements that the YL band is enhanced in the PL spectra of those samples if their MOCVD growth is carried out with a decrease of pressure, temperature, or flow rate of NH3. Furthermore, a strong dependence of YL band intensity on the carbon concentration is found by secondary ion mass spectroscopy (SIMS) measurements, demonstrating that the increased carbon-related defects in these samples are responsible for the enhancement of the YL band.
Highlights
GaN-based third-generation semiconductor materials, including InN, GaN, AlN and their alloys have attracted extensive attention owing to their broad applications of GaN-based photonic and electronic devices, such as light-emitting diodes (LEDs) [1,2], laser diodes (LDs) [3–5], photodetectors (PDs) [3], and high electron mobility transistors (HEMTs) [6–8]
It is found that the blue luminescence (BL) intensity and yellow luminescence (YL) intensity increase signifificantly when growth pressure decreases from 200 Torr to 50 Toorrrr,aannddtthheeyybbeeccoommee llaarrggeerr tthhaann tthhee UUVVLL iinntteensity when the growth pressure is reduced to 50 Toorrr
Three sets of unintentionally doped GaN (u-GaN) samples with different carbon concentrations are grown by controlling the growth pressure, temperature and flow rate of NH3
Summary
GaN-based third-generation semiconductor materials, including InN, GaN, AlN and their alloys have attracted extensive attention owing to their broad applications of GaN-based photonic and electronic devices, such as light-emitting diodes (LEDs) [1,2], laser diodes (LDs) [3–5], photodetectors (PDs) [3], and high electron mobility transistors (HEMTs) [6–8]. Nanomaterials 2018, 8, x FOR PEER REVIEW The investigation on the mechanism of the YL band in u-GaN caann bbeehheellppffuullffoorrssttuuddyyininggththeeimimppuurirtiytyananddddefeefcetcrterlealtaetdedlulmuminiensecsecnecnecieniInIII-InIi-tnridtreids,essu, cshucahs aInsGInaGNa,NA,lGAalGNaNanadnIdnIAnlAGlaGNa.NL.
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