Angular-dependent Raman study of a- and s-plane InN

Abstract

Debo Ajagunna Adebowale Olufunso (Debo) Ajagunna-Brief Biography Adebowale Olufunso (Debo) Ajagunna, a native of Nigeria moved to Greece and obtained his PhD in Physics from the University of Crete in 2011. His thesis was entitled "Heteroepitaxy of InN on silicon (111) and R-Plane sapphire substrates [1] " and it was performed under the supervision of Prof. Alexandros Georgakilas. [2] At the time he also served a church in Heraklion. The church is composed of expatriate converts, many of them from Nigeria. Afther his PhD Debo return back to Nigeria, to be with his wife and three children. On May 1, 2012 he was praying with members of his former congregation in Ikare-Akoko, a city in the southwestern Nigerian state of Ondo, when armed robbers entered the church building."Everyone ran for their life," said Eleni Melirrytos, a member of the Omonia Church of Christ in Athens, Greece, and longtime friend of Ajagunna. "There was a pregnant lady who got shot and was asking for help. Debo had already left the room but came back to help her. That is when he got shot." Ajagunna died from his injuries. The pregnant woman (and her unborn child) survived the attack.

Polarized Raman and photoluminescence studies of a sub-micron sized hexagonal AlGaN crystallite for structural and optical properties

“…It is well known that the possibility of formation of defects and stacking faults along the c‐ plane is more probable as compared with those in the m‐ plane. In other words, the defect density along m‐ plane is comparatively less than that of c‐ plane . Because of the non‐centrosymmetric nature of wurtzite crystal, there will be a spontaneous polarization along the c ‐axis of the crystal.…”

“…Whereas, the optical properties of a homogenous single crystal along m ‐plane are expected to be comparatively free from spontaneous polarization as well as strain‐related internal electric fields, and it shows high optical quality with sharp band edge peak. Therefore, in case of III‐nitrides, it is advisable that the m ‐plane oriented crystallites are more favorable for making high performance devices than that with the c ‐plane oriented crystals …”

“…In the context of understanding the crystalline properties of the sub‐micron sized cystallite, the Raman spectroscopy is not only a very efficient non‐destructive characterization tool for the phase confirmation of the sample but also the fact that the polarized Raman spectrum is capable to investigate the crystallographic orientation in agreement with selection rules . There are several reports available for polarized as well as angular dependent polarized Raman studies collected from a single spot on material . However, the polarized Raman studies alone may not be sufficient to understand crystalline nature of the crystallites.…”

“…The performances of such devices are dependent on both the crystalline as well as the electronic properties of the material. It is reported that the III‐nitrides grown along the c‐ axis [0001] with polar orientation lead to a huge amount of intrinsic electric field, which degrades the efficiency of light emitting devices . Therefore, it is very important to study the crystallographic orientation dependent optical properties of these III‐nitrides .…”

“…It is reported that the III‐nitrides grown along the c‐ axis [0001] with polar orientation lead to a huge amount of intrinsic electric field, which degrades the efficiency of light emitting devices . Therefore, it is very important to study the crystallographic orientation dependent optical properties of these III‐nitrides . The problem due to the polarity of the crystals can be overcome for the low‐dimensional systems by allowing the growth along nonpolar directions normal to a ‐ {1–120} and m ‐plane {1–100} instead of the c‐ plane {0001} .…”