Optical and electrical properties of Mg-doped AlN nanowires grown by molecular beam epitaxy

Abstract

In this paper, the optical and electrical properties of Mg-doped AlN nanowires are discussed. At room temperature, with the increase of Mg-doping concentration, the Mg-acceptor energy level related optical transition can be clearly measured, which is separated about 0.6 eV from the band-edge transition, consistent with the Mg activation energy in AlN. The electrical conduction measurements indicate an activation energy of 23 meV at 300 K-450 K temperature range, which is significantly smaller than the Mg-ionization energy in AlN, suggesting the p-type conduction being mostly related to hopping conduction. The free hole concentration of AlN:Mg nanowires is estimated to be on the order of 10 16 cm À3 , or higher. V

Molecular beam epitaxy growth of Al-rich AlGaN nanowires for deep ultraviolet optoelectronics

“…The excellent current conduction in such an Al-rich AlGaN nanowire LED is directly related to the significantly enhanced Mg-dopant incorporation in the nanowire structure and the resultant Mg impurity band conduction. 48,49 The room-temperature electroluminescence (EL) spectra measured from different devices are shown in Fig. 4(c).…”

Recent Advances on p-Type III-Nitride Nanowires by Molecular Beam Epitaxy

“…Moreover, to reduce Mg surface desorption, a relatively low substrate temperature is used. The typical growth condition includes a nitrogen flow rate of 1 sccm, a nitrogen plasma power of 350 W, and a substrate temperature of 800 • C. Al and Mg fluxes are in the range of 2-6 × 10 −8 Torr and 3 × 10 −9 to 9 × 10 −8 Torr, respectively [42,84,85]. Under optimized growth conditions, relatively uniform Mg-doped AlN nanowires can be obtained, as shown in Figure 7a.…”

“…The properties of these Mg-doped AlN nanowires, however, are largely determined by various defect energy levels in the ultra-wide-bandgap AlN, e.g., only defect-related optical emission can be measured [78]. Recently, with the use of MBE, Mg-doped AlN nanowires with excellent optical and electrical properties are obtained [42,[83][84][85][86], which represents a critical step towards AlN nanowire-based deep UV optoelectronic devices. In this section, we discuss recent progress made on Mg-doped AlN nanowires grown by MBE, and their applications to deep UV LEDs and lasers.…”

“…Detailed studies further indicate that the growth condition of such GaN nanowire templates plays an important role on the formation of the AlN nanowire segment on top [42,53,84,85]. Moreover, to reduce Mg surface desorption, a relatively low substrate temperature is used.…”

“…To promote nanowire formation, a spontaneously formed GaN nanowire template is grown first [42,[84][85][86]. Detailed studies further indicate that the growth condition of such GaN nanowire templates plays an important role on the formation of the AlN nanowire segment on top [42,53,84,85].…”