| CZECH NANO TEAM | Physics of Nanostructures and Nanotechnologies

• Research of epitaxial growth from the vapor phase (GaP/GaAs, GaP/GaP, GaP/Mo, GaN/Al2O3, GaAlN/Al2O3, and InP/InP) and from the liquid phase (GaP:Zn,O/GaP, GaP:N/ GaP, GaAs:Si/GaAs, GaAlAs/GaAs, GaInAsP/InP, GaInP2/GaAs and Si/Si).

• Optimisation of the prepared structures for light emitting diodes in visible and infrared part of the spectra, injection lasers, secondary electron emission and photodetectors. The most important results have been related to the preparation of the DC PBH lasers throughout the spectral 1.07 to 1.67 m with threshold current approaching 10 mA at RT, elastically strained quantum wells and GaInP2/GaAs solar cell structures.

• Recently etching study of the InAs and GaSb , surface passivation and electrochemical anodization of the InP and InAs.

• The supervisor of 3 successful diploma theses, 3CSc theses.

Publications:

Author and co-author of more than 76 scientific publications to which more than 21 references appeared in the literature. Amongst these there are joint papers with the Lancaster University UK, Institut für Kristallzüchtung-Berlin, University of Surrey UK, Siemens AG, Regensburg, Germany and 4.Physikalisches Institut of the Stuttgart University, Germany.

Selected study stays abroad:

• In 1989 two months stay at Epiquip, ( MOVPE apparatus producer), Lund, Sveden.

• In 1992 two months stay at Kristall labor of the Stuttgart University.

• In 1994 two months stay at University of Surrey arranget by British Telecom.

• In 1995 six months stay at Institut für Kristallzüchtung Berlin (colaboration with SiemensAG).

• In 2001 three months stay at Physics Dept. of the Lancaster University UK extended in 2002 for next 12 months.

Selected solved project:

• EPSRC Grant GR/R43334/01,GB, (2002-2003, one year) “Novel chemical etching techniques for the processin of InAs and its solid solutions“.

Selected related publications from last 5 years:

• K. Žďánský, J. Zavadil, D. Nohavica, S. Kugler: Degradation of commercial high-brightness GaP:N green light emitting diodes, J. Appl. Phys. 83, N12, (1998), str.1

• D. Nohavica, P. Gladkov, K. Ždánský: Preparation and properties of thick not intentionally doped GaInP(As)/GaAs layers, Nucl. Instrum. & Methods A 434 (1999) 164

• D. Nohavica, A. Krier: Point defects creation during surface reconstruction, Condensed Matter and Materials Conference of the UK Institute of Physics (CMMP-2002), Brighton, UK, April 2002

• D. Nohavica, A. Krier: „Structural modifications of InAs based materials for mid-infrared optoelectronic devices”, ibid.

• D.Nohavica, A. Krier: „Organic acid-based etchants for InAs, GaSb and related material systems” - Mid-infrared Network Meeting, October 2000, Shefdield, UK

• D. Nohavica: „Structural modification of InAs based materials for mid-infrared optoelectronic devices“,Mid-infrared Network meeting, July 2002, Imperial College, London

Group members:

Dušan Nohavica, Petar Gladkov, Jiří Zelinka, Běla Pilmanová

Main Research Subject:

The first subject is utilization of the epitaxial technique facilities in the Institute of Radio Engineering and Electronics for preparation of the binary and ternary A3B5 semiconductors.

The second subject is a porous A3B5 materials preparation in developed electrochemical etching system.

The third subjekt is characterization of thin self-organized porous layers on top of the binary and ternary epitaxial layers with the use of two complementary and nondestructive techniques: optical spectroscopy (both photoluminescence and micro-cathodoluminescence) and structural characterization by means of scanning electron microscopy (SEM).

Conventional and high resolution transmission electron microscopy (TEM, HRTEM) is used for the determination of the local structure at the atomic level of various materials. Special emphasis will be given to the understanding of the defect content and the morphology of these structures in relation to the various parameters of pores generation.

Selected Specific Equipment:

Conventional optical microscopy (Olympus BX50 with NIC and magnification up to 1000x) is used for preliminary observations.

The room temperature and helium temperature PL measurements are performed on a spectrometer capable in the range 0.2 – 5 μm.

Part of the SEM characterization, especially the spectral resolved μCL will be worked out on a SEM “Philips ” equipped with Oxford Instruments INKA EDX analyzer.

Additional recent selected publications by group members:

• Dimroth, P. Gladkov and A. Bett:: Atomic incorporation during the GaSb MOVPE epitaxial growth-correlation with the low tempetature photoluminescence, To be presented on the 2004 international MOVPE conference.

• Carsten Agert, Peter S. Gladkov and Andreas W. Bett: Origin of the photoluminescence line at 0.8 eV in undoped and Si-doped GaSb grown by MOPE, Semicond. Sci. Technol.17 (2002) p.39

• P. Gladkov and J. Weber: Low temperature photoluminescence properties of p- and n-type Alx Ga (1-x)As with x>0.42, Czechoslovak Journal of Physics 49[5] (1999) p.823

• P. Gladkov, C. Agert, A. Bett and J. Weber:Origin of the BE4 photoluminescence line in GaSbs ubmitted to the Semicond. Sci. Technol.

• P. Gladkov, M. Meussel, A. Bett, Ph. Komninou, J. Weber: Nature of the hotoluminescence line related with the “inverted” interface GaAs on lattice matched InGaP by MOVPE, submitted to the Journal of Crystal Growth.