Stacking faults as quantum wells in nanowires: Density of states, oscillator strength and radiative efficiency

Abstract

We investigate the nature of excitons bound to I1 basal-plane stacking faults [(I1;X)] in GaN nanowire ensembles by continuous-wave and time-resolved photoluminescence spectroscopy. Based on the linear increase of the radiative lifetime of these excitons with temperature, they are demonstrated to exhibit a two-dimensional density of states, i. e., a basal-plane stacking fault acts as a quantum well. From the slope of the linear increase, we determine the oscillator strength of the (I1;X) and show that the value obtained reflects the presence of large internal electrostatic fields across the stacking fault. While the recombination of donor-bound and free excitons in the GaN nanowire ensemble is dominated by nonradiative phenonema already at 10 K, we observe that the (I1;X) recombines purely radiatively up to 60 K. This finding provides important insight into the nonradiative recombination processes in GaN nanowires. First, the radiative lifetime of about 6 ns measured at 60 K sets an upper limit for the surface recombination velocity of 450 cm/s considering the nanowires mean diameter of 105 nm. Second, the density of nonradiative centers responsible for the fast decay of donor-bound and free excitons cannot be higher than 2x10^16 cm^-3. As a consequence, the nonradiative decay of donor-bound excitons in these GaN nanowire ensembles has to occur indirectly via the free exciton state.

References in corpus (7)

• Why does wurtzite form in nanowires of III-V zinc-blende semiconductors?
• Twinning superlattices in indium phosphide nanowires
• A growth diagram for plasma-assisted molecular beam epitaxy of GaN nanocolumns on Si(111)
• Investigating the origin of the nonradiative decay of bound excitons in GaN nanowires
• Sub-meV linewidth in GaN nanowire ensembles: absence of surface excitons due to the field-ionization of donors
• Cathodoluminescence of stacking fault bound excitons for local probing of the exciton diffusion length in single GaN nanowires
• Quantum-confined single photon emission at room temperature from Silicon carbide tetrapods

Cited by in corpus (10)

• Molecular beam epitaxy of single crystalline GaN nanowires on a flexible Ti foil
• Molecular Beam Epitaxy of GaN Nanowires on Epitaxial Graphene
• Observation of dielectrically confined excitons in ultrathin GaN nanowires up to room temperature
• High-temperature growth of GaN nanowires by molecular beam epitaxy: toward the materials quality of bulk GaN
• Carrier diffusion in GaN -- a cathodoluminescence study. I: Temperature-dependent generation volume
• Nature of excitons bound to inversion domain boundaries: Origin of the 3.45-eV luminescence lines in spontaneously formed GaN nanowires on Si(111)
• Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion
• External control of GaN band bending using phosphonate self-assembled monolayers
• Crystal-phase quantum dots in GaN quantum wires
• Comprehensive investigation on the correlation of growth, structural and optical properties of GaN nanowires grown on Si(111) substrates by plasma assisted molecular beam epitaxy technique