Temperature dependence of Mg-H local vibrational modes in heavily doped InN:Mg

Abstract

We have studied the temperature dependence and anharmonic coupling of the local vibrational modes (LVMs) associated with Mg-H complexes in heavily doped InN:Mg. Two main LVM peaks are observed which are probably related to two different H-impurity bond lengths. The temperature dependence of the higher-frequency mode, which exhibits a monotonic frequency downshift and broadening with increasing temperature, can be explained by LVM dephasing due to acoustic phonon scattering. The lower-frequency mode displays an anomalous behavior as its frequency decreases initially and then starts to increase linearly above room temperature. The anharmonic coupling of the lower-frequency mode to a molecular mode of the impurity complex is suggested as a possible cause for this behavior.

Mg and In Codoped p-type AlN Nanowires for pn Junction Realization

“…In such a context, the dramatic increase in Mg content in Mg/In codoped AlN NWs reported in the present work could be favourable to a reduction of the acceptor ionization energy similarly to the behaviour of GaN layers. This is supported by the fact that the maximum Mg doping level in presence of In, namely 1.5 × 10 20 Mg/cm 3 , is almost one order of magnitude higher than the Mg level reported by Taniyasu [12], suggesting the formation of a band of defects and a decrease of the effective ionization energy. Regardless of the ionization energy, either 630 meV corresponding to isolated impurities or lower, the high density of Mg dopants further supports a hopping mechanism.…”

“…The intensity of the Mg–H modes was multiplied by 25 for clarity. (d) Detail of the spectral range corresponding to the Mg–H modes of samples A to D. GaN NW and InN bulk Mg-doped references were also included.…”

Carbon doping of GaN: Proof of the formation of electrically active tri-carbon defects

“…2). Analogous behavior was observed, for example, in Raman investigations of Mg-H complexes in InN:Mg and in IR absorption of Se-related complexes in AlSb:Se,H,D, 28,29 which the authors explained by resonant interactions between the defect vibration and optical phonons. Since the basal tri-carbon defect configuration is symmetric (C2v molecule symmetry), its antisymmetric stretching mode might couple more strongly with the phonon system than that of the asymmetric axial configuration.…”

Functional Mn–Mgk cation complexes in GaN featured by Raman spectroscopy

“…Raman spectroscopy is particularly suitable to investigate impurities and impurity complexes in semiconductors 6 due to its sensitivity to variations in the structural and electronic properties of the material under study. In the case of doping of nitrides with Mg, this technique was decisive to identify the Mg-H complexes 7,8 responsible for the low efficiency of the Mg activation, and for the consequent poor p-type conductivity especially in GaN:Mg. [9][10][11] While Mg is the most relevant p-type dopant in GaN, and is employed in the majority of optoelectronic devices based on GaN, Mn generated interest lately for its potential in spintronics, and particularly in the perspective of turning p-type Mn-doped GaN (i.e., (Ga,Mn)N:Mg) into a ferromagnetic dilute magnetic semiconductor with a high Curie transition temperature. 12 Moreover, the recent demonstration of unexpected (infrared) optical and magnetic responses in (Ga,Mn)N:Mg, 5 has opened appealing fundamental and technological perspectives for this system.…”