Optical modulation techniques applied in the analysis of chalcopyrite semiconductor heterostructures

Anestou, K; Papadimitriou, D

dc.contributor.author	Anestou, K	en
dc.contributor.author	Papadimitriou, D	en
dc.date.accessioned	2014-03-01T02:11:50Z
dc.date.available	2014-03-01T02:11:50Z
dc.date.issued	2012	en
dc.identifier.issn	00223727	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29959
dc.subject.other	Band energy	en
dc.subject.other	Biaxial strains	en
dc.subject.other	Chalcopyrite layers	en
dc.subject.other	Chalcopyrite semiconductor	en
dc.subject.other	Device technologies	en
dc.subject.other	Effective strain	en
dc.subject.other	Elastic strain	en
dc.subject.other	Elasticity theory	en
dc.subject.other	Energy shift	en
dc.subject.other	Epitaxially grown	en
dc.subject.other	Hydrostatic strain	en
dc.subject.other	Low temperatures	en
dc.subject.other	Monocrystalline	en
dc.subject.other	Optical modulation technique	en
dc.subject.other	Partial anions	en
dc.subject.other	Photoreflectance spectroscopy	en
dc.subject.other	Quaternary alloys	en
dc.subject.other	Semiconductor heterostructures	en
dc.subject.other	Thermal strain	en
dc.subject.other	Thick layers	en
dc.subject.other	Elasticity	en
dc.subject.other	Epitaxial growth	en
dc.subject.other	Frequency modulation	en
dc.subject.other	Gallium	en
dc.subject.other	Gallium alloys	en
dc.subject.other	Heterojunctions	en
dc.subject.other	Interfaces (materials)	en
dc.subject.other	Light modulation	en
dc.subject.other	Solar absorbers	en
dc.subject.other	Copper compounds	en
dc.title	Optical modulation techniques applied in the analysis of chalcopyrite semiconductor heterostructures	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0022-3727/45/21/215305	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0022-3727/45/21/215305	en
heal.identifier.secondary	215305	en
heal.publicationDate	2012	en
heal.abstract	The structural properties of chalcopyrite single crystals and monocrystalline epitaxial layers of ternary (CuGaSe2, CuInSe2, CuGaS2, CuInS2) and quaternary (CuIn1xGaxSe2) chalcopyrite absorbers with applications in solar-cell device technology are analysed by optical modulation techniques. Photoreflectance (PR) Spectroscopy is applied at room and low temperatures to quantify elastic strain effects. With respect to bulk chalcopyrites, epitaxially grown layers exhibit band energy shifts due to mismatch and thermal strain evolving in semiconductor heterostructures. In the uppermost 100nm of the 500nm thick layers, the magnitude of the respective stress measures 100MPa, at 300K, and 400MPa, at 20K, and is reduced by up to 50% compared with the stress at the chalcopyrite/GaAs-substrate interface. The overall strain calculated from the energy shift of the PR spectra is compared with the strain calculated in terms of elasticity theory. The coexistence of biaxial and hydrostatic strain due to partial anion/cation substitution in ternary to form quaternary chalcopyrite layers is also discussed. Based on the evaluation of effective strain as a result of both hydrostatic and biaxial strain in quaternary chalcopyrite layers CuIn1xGaxSe2 and the evaluation of the PR spectra of the layers, the band energies of the respective non-strained quaternary alloy with x=0.19 are determined to be Ea=1.09eV and Eb=1.22eV. © 2012 IOP Publishing Ltd.	en
heal.journalName	Journal of Physics D: Applied Physics	en
dc.identifier.doi	10.1088/0022-3727/45/21/215305	en
dc.identifier.volume	45	en
dc.identifier.issue	21	en