@PHDTHESIS{Lahnemann_2013,
  author = {Jonas L\"ahnemann},
  title = {Luminescence of group-{III-V} nanowires containing heterostructures},
  school = {Humboldt Universit\"at zu Berlin},
  year = {2013},
  month = {July},
  abstract = {In this thesis, the spectral and spatial luminescence distribution
	of heterostructures in self-induced nanowires (NWs) is investigated
	by cathodoluminescence spectroscopy in a scanning electron microscope.
	This method is complemented by data from both continuous and time-resolved
	micro-photoluminescence measurements. Three different structures
	are considered: (i) GaAs NWs containing segments of the wurtzite
	(WZ) and zincblende (ZB) polytypes, (ii) GaN microcrystals overgrown
	on GaN NWs, and (iii) (In,Ga)N insertions embedded in GaN NWs.
	
	The polytypism of GaAs NWs results in complex emission spectra. The
	observation of luminescence either exclusively at energies below
	the ZB band gap or also at higher energies is explained by differences
	in the distribution of ZB and WZ segment thicknesses. Measurements
	at room temperature suggest that the band gap of WZ GaAs is at least
	55 meV larger than that of the ZB phase.
	
	The luminescence spectra of the GaN microcrystals contain distinct
	emission lines associated with stacking faults (SFs). SFs essentially
	constitute ZB quantum wells of varying thickness in a WZ matrix and
	it is shown that their emission energy is dominated by the spontaneous
	polarization. Through a detailed statistical analysis of the emission
	energies of the different SF types, emission energies of 3.42, 3.35
	and 3.29 eV are determined for the intrinsic (I1 and I2) as well
	as the extrinsic SFs, respectively. From the corresponding energy
	differences, an experimental value of -0.022C/m² is derived for the
	spontaneous polarization of GaN.
	
	The importance of both carrier localization and the quantum confined
	Stark effect induced by the piezoelectric polarization is shown for
	the luminescence of (In,Ga)N insertions in GaN NWs. Not only localized
	excitons, but also electrons and holes individually localized at
	different potential minima contribute to the observed emission.},
  url = {http://nbn-resolving.de/urn:nbn:de:kobv:11-100212149},
  doi = {10.18452/16797}
}