Dynamics of mass transport during nanohole drilling by local droplet etching

Local droplet etching (LDE) utilizes metal droplets during molecular beam epitaxy for the self-assembled drilling of nanoholes into III/V semiconductor surfaces. An essential process during LDE is the removal of the deposited droplet material from its initial position during post-growth annealing. This paper studies the droplet material removal experimentally and discusses the results in terms of a simple model. The first set of experiments demonstrates that the droplet material is removed by detachment of atoms and spreading over the substrate surface. Further experiments establish that droplet etching requires a small arsenic background pressure to inhibit re-attachment of the detached atoms. Surfaces processed under completely minimized As pressure show no hole formation but instead a conservation of the initial droplets. Under consideration of these results, a simple kinetic scaling model of the etching process is proposed that quantitatively reproduces experimental data on the hole depth as a function of the process temperature and deposited amount of droplet material. Furthermore, the depth dependence of the hole side-facet angle is analyzed.

[1]  V. A. Gorokhov,et al.  The investigation of P‐ and As diffusion in liquid Gallium , 1984 .

[2]  O. Schmidt,et al.  Ultra-small excitonic fine structure splitting in highly symmetric quantum dots on GaAs (001) substrate , 2013 .

[3]  J. A. Töfflinger,et al.  Single-photon emission from InGaAs quantum dots grown on (111) GaAs , 2010 .

[4]  J. Leem,et al.  Nanoscale InGaAs concave disks fabricated by heterogeneous droplet epitaxy , 2000 .

[5]  S. Sanguinetti,et al.  Concentric Multiple Rings by Droplet Epitaxy: Fabrication and Study of the Morphological Anisotropy , 2010, Nanoscale research letters.

[6]  Y. Mazur,et al.  Self-assembled InAs quantum dot formation on GaAs ring-like nanostructure templates , 2007, Nanoscale Research Letters.

[7]  S. Mendach,et al.  Highly uniform and strain-free GaAs quantum dots fabricated by filling of self-assembled nanoholes , 2009 .

[8]  J. A. Venables,et al.  Rate equation approaches to thin film nucleation kinetics , 1973 .

[9]  A. Schramm,et al.  Regimes of GaAs quantum dot self-assembly by droplet epitaxy , 2007 .

[10]  S. C. Hardy,et al.  The surface tension of liquid gallium , 1985 .

[11]  C. Heyn,et al.  Excitonic lifetimes in single GaAs quantum dots fabricated by local droplet etching , 2012 .

[12]  Gregory J. Salamo,et al.  Super Low Density InGaAs Semiconductor Ring-Shaped Nanostructures , 2008 .

[13]  K. Reichelt,et al.  Nucleation and growth of thin films , 1988 .

[14]  D. Fuster,et al.  Fundamental role of arsenic flux in nanohole formation by Ga droplet etching on GaAs(001) , 2014, Nanoscale Research Letters.

[15]  C. Heyn,et al.  Electric Properties of Semiconductor Nanopillars , 2014, Journal of Electronic Materials.

[16]  T. Mano,et al.  Self-assembly of laterally aligned GaAs quantum dot pairs , 2006 .

[17]  J. M. Moison,et al.  Self‐organized growth of regular nanometer‐scale InAs dots on GaAs , 1994 .

[18]  C. Heyn,et al.  Vertically stacked quantum dot pairs fabricated by nanohole filling , 2014, Nanotechnology.

[19]  G. Salamo,et al.  Formation of GaAs Double Rings Through Gallium Migration and Nanodrilling , 2011 .

[20]  W. Ostwald,et al.  Über die vermeintliche Isomerie des roten und gelben Quecksilberoxyds und die Oberflächenspannung fester Körper , 1900 .

[21]  Zh. M. Wang,et al.  Various Quantum- and Nano-Structures by III–V Droplet Epitaxy on GaAs Substrates , 2009, Nanoscale research letters.

[22]  T. Noda,et al.  Atomic scale analysis of self assembled GaAs/AlGaAs quantum dots grown by droplet epitaxy , 2010 .

[23]  S. Sanguinetti,et al.  Optical transitions in quantum ring complexes , 2005, cond-mat/0509625.

[24]  M. Schmidt,et al.  Air-gap heterostructures , 2011 .

[25]  A. Stemmann,et al.  Dynamics of self-assembled droplet etching , 2009 .

[26]  C. D. Thurmond.  Phase equilibria in the GaAs and the GaP systems , 1964 .

[27]  Scheffler,et al.  GaAs equilibrium crystal shape from first principles. , 1996, Physical review. B, Condensed matter.

[28]  A. Stemmann,et al.  Local droplet etching of nanoholes and rings on GaAs and AlGaAs surfaces , 2008 .

[29]  S. Mendach,et al.  Local etching of nanoholes and quantum rings with InxGa1−x droplets , 2009 .

[30]  B. Alén,et al.  Formation of Lateral Low Density In(Ga)As Quantum Dot Pairs in GaAs Nanoholes , 2009 .

[31]  S. Sanguinetti,et al.  Exciton fine structure in strain-free GaAs/Al 0.3 Ga 0.7 As quantum dots: Extrinsic effects , 2008 .

[32]  T. Chikyow,et al.  MBE Growth Method for Pyramid-Shaped GaAs Micro Crystals on ZnSe(001) Surface Using Ga Droplets , 1990 .

[33]  J. Tersoff,et al.  Running Droplets of Gallium from Evaporation of Gallium Arsenide , 2009, Science.

[34]  C. Heyn,et al.  Scaling of the structural characteristics of nanoholes created by local droplet etching , 2014 .

[35]  C. Heyn,et al.  Highly versatile ultra-low density GaAs quantum dots fabricated by filling of self-assembled nanoholes , 2012 .

[36]  P. Smereka,et al.  Unified model of droplet epitaxy for compound semiconductor nanostructures: Experiments and theory , 2012, 1211.0486.

[37]  Anupam Madhukar,et al.  Nature of strained InAs three‐dimensional island formation and distribution on GaAs(100) , 1994 .

[38]  C. Heyn.  Kinetic model of local droplet etching , 2011 .

[39]  Savage,et al.  Kinetic pathway in Stranski-Krastanov growth of Ge on Si(001). , 1990, Physical review letters.

[40]  H. Jehn.  Nucleation and Growth of Thin Films , 1992 .

[41]  J. S. Kim,et al.  Near room temperature droplet epitaxy for fabrication of InAs quantum dots , 2004 .

[42]  Zhichuan Niu,et al.  Complex quantum ring structures formed by droplet epitaxy , 2006 .

[43]  Baolai Liang,et al.  Nanoholes fabricated by self-assembled gallium nanodrill on GaAs(100) , 2007 .

[44]  S. Yoon,et al.  Investigation of the fabrication mechanism of self-assembled GaAs quantum rings grown by droplet epitaxy , 2008, Nanotechnology.

[45]  A. Stemmann,et al.  Influence of Ga coverage and As pressure on local droplet etching of nanoholes and quantum rings , 2009 .

[46]  A. Stemmann,et al.  Nanohole formation on AlGaAs surfaces by local droplet etching with gallium , 2009 .

[47]  M. Volmer,et al.  Keimbildung in übersättigten Gebilden , 1926 .

[48]  Eun-Soo Kim,et al.  Origin of nanohole formation by etching based on droplet epitaxy. , 2014, Nanoscale.

[49]  James L. Merz,et al.  Molecular‐beam epitaxy growth of quantum dots from strained coherent uniform islands of InGaAs on GaAs , 1994 .