Growth and optical investigations of high quality individual CdTe/(Cd,Mg)Te core/shell nanowires

Abstract

CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.

TEM Study of the Structural Properties of Nanowires Based on Cd, Zn, Te grown by MBE on Silicon Substrates

“…Lately, the successful activation of the NBE emission (2.33 eV) for the ZnTe NW has been reported by Wojnar et al [8] as a result of the surface states passivation [9,10] achieved by coating the NW with a higher band gap shell (ZnMgTe). The use of the Si substrates in the work [8] was the first attempt to integrate the II-VI NWs with the well-established Si technology * corresponding author; e-mail: kaleta@ifpan.edu.pl as so far the NWs were grown on the GaAs substrates in orientations (001), (110), (111)B [8].…”

“…The II-VI NWs were grown on Si (111) substrate using similar procedure to Ref. [9]. Firstly, the Si substrate was inserted into the first MBE chamber, where 1 nm gold layer deposition took place.…”

“…In the case of the CdTe NWs growth (Fig. 1c), it needs an initialization process by using 4 min deposition of the ZnTe in 380 • C firstly [9], due to the high mismatch between the CdTe and the Si substrate (Table I). After the temperature reduction to 350 • C the CdTe deposition takes place.…”

“…The Burgers vector circuits were drawn to determine the dislocation character of the defects observed at the interface. All these dislocations are 60 • type with 1/2 [1][2][3][4][5][6][7][8][9][10] Burgers vectors lying in the (111) plane and projected onto the direction. Chen and Wang proposed two different misfit dislocation network models on the interface between c-BN single crystal and (111) diamond (≈ 1.4% misfit).…”

“…The use of the Si substrates in the work [8] was the first attempt to integrate the II-VI NWs with the well-established Si technology * corresponding author; e-mail: kaleta@ifpan.edu.pl as so far the NWs were grown on the GaAs substrates in orientations (001), (110), (111)B [8]. Additionally, the substantial differences between the GaAs(111)B and the Si(111) substrates used for ZnTe/ZnMgTe core/shell NWs grown by the molecular beam epitaxy (MBE) via vapor-liquid-solid (VLS) mechanism [11] with gold droplets as the catalyst were discussed in [9]. (111)NWs grown on GaAs (111)B were perpendicular to the substrate surface, whereas the (111)NWs grown on the Si(111) had a random growth orientation in reference to the Si substrate.…”