Local Vibrational Modes in p-Type GaN Observed by Raman Scattering

p-Type dopant incorporation and surface charge properties of catalyst-free GaN nanowires revealed by micro-Raman scattering and X-ray photoelectron spectroscopy

“…This is the rst report on the observation of such Mg-induced LVM in GaN nanowire structures and it is in quantitative agreement with previous reports on Mg-doped GaN epilayers. 41,44,45 Moreover, in the Raman spectra around 2200 cm À1 in Fig. 2(b), three distinct modes at 2139 cm À1 , 2166 cm À1 and 2186 cm À1 are detected for nanowire samples with T Mg above 250 C. These spectroscopic features can be attributed to the LVM associated with Mg-H complexes or H-decorated nitrogen vacancies.…”

High‐energy vibrational modes in nitrogen‐doped ZnO

“…McCluskey et al 20 performed infrared spectroscopy on an undoped single crystal ZnO sample and observed an oxygen–hydrogen stretch mode at 3326.3 cm –1 , in good agreement with the theoretical predictions for hydrogen in an antibonding configuration by van de Walle 21. Considering again the similarity to GaN:Mg, where in infrared absorption spectra 22 and in Raman spectra 18 of semi‐insulating samples a mode at 3125 cm –1 and 3123 cm –1 , respectively, was observed, the absence of any line above 3000 cm –1 in our Raman spectra of ZnO:N might indicate a binding mechanism of the incorporated nitrogen and hydrogen similar to that in p‐type GaN.…”

“…Four of these modes found by Brandt et al 17 were assigned to vibrational modes of Mg–H complexes and the presence of diatomic molecules such as N 2 or H 2 , alternatively to a H‐decorated native defect. Harima et al 18 showed the correlation of hydrogen incorporation during different growth conditions. Their results support an interpretation in terms of a reorientation of initial Mg Ga –N–H complexes and the formation of new complexes with electrical inactive hydrogen 19.…”

Physical Properties of AlGaN/GaN Heterostructures Grown on Vicinal Substrates

“…A characteristically broad band below 400 cm À1 was observed in the Raman spectra of our vicinal substrates taken after heterostructure growth and in situ anneal at 800°C under nitrogen. Harima 53,65 found that this broad band below 400 cm À1 was not a phonon signal but rather an electronic signal attributed to what is called the inter-valence-band transition of the hole (IVBTH), and that its amplitude was annealing temperature dependent. The appearance of the broad band is evidence of p-type conductivity.…”

“…The appearance of the broad band is evidence of p-type conductivity. 53,65 After the ex situ anneal at 800°C was performed, Raman measurements were repeated, and this broad signal was weaker. Since the intensity of this Raman continuum band is nearly proportional to the hole density, 53,65 the integrated area of the IVBTH peak for our heterostructures before ex situ anneal was analyzed by integrating the area under the band extending from 260 cm À1 to 400 cm À1 .…”