Direct imaging of p-n junction in core-shell GaN wires.

While core-shell wire-based devices offer a promising path toward improved optoelectronic applications, their development is hampered by the present uncertainty about essential semiconductor properties along the three-dimensional (3D) buried p-n junction. Thanks to a cross-sectional approach, scanning electron beam probing techniques were employed here to obtain a nanoscale spatially resolved analysis of GaN core-shell wire p-n junctions grown by catalyst-free metal-organic vapor phase epitaxy on GaN and Si substrates. Both electron beam induced current (EBIC) and secondary electron voltage constrast (VC) were demonstrated to delineate the radial and axial junction existing in the 3D structure. The Mg dopant activation process in p-GaN shell was dynamically controlled by the ebeam exposure conditions and visualized thanks to EBIC mapping. EBIC measurements were shown to yield local minority carrier/exciton diffusion lengths on the p-side (∼57 nm) and the n-side (∼15 nm) as well as depletion width in the range 40-50 nm. Under reverse bias conditions, VC imaging provided electrostatic potential maps in the vicinity of the 3D junction from which acceptor Na and donor Nd doping levels were locally determined to be Na = 3 × 10(18) cm(-3) and Nd = 3.5 × 10(18) cm(-3) in both the axial and the radial junction. Results from EBIC and VC are in good agreement. This nanoscale approach provides essential guidance to the further development of core-shell wire devices.

[1]  Yong-Ho Ra,et al.  Single nanowire light-emitting diodes using uniaxial and coaxial InGaN/GaN multiple quantum wells synthesized by metalorganic chemical vapor deposition. , 2014, Nano letters.

[2]  Thomas J. Kempa,et al.  Facet-selective growth on nanowires yields multi-component nanostructures and photonic devices. , 2013, Journal of the American Chemical Society.

[3]  K. Hamada,et al.  Sensitive Site-Specific Dopant Mapping in Scanning Electron Microscopy on Specimens Prepared by Low Energy Ar+ Ion Milling , 2013 .

[4]  Erik Lind,et al.  Combining axial and radial nanowire heterostructures: radial Esaki diodes and tunnel field-effect transistors. , 2013, Nano letters.

[5]  P. Tchoulfian,et al.  Thermoelectric and micro-Raman measurements of carrier density and mobility in heavily Si-doped GaN wires , 2013 .

[6]  Jonathan J. Wierer,et al.  Spatial mapping of efficiency of GaN/InGaN nanowire array solar cells using scanning photocurrent microscopy. , 2013, Nano letters.

[7]  Zetian Mi,et al.  Breaking the carrier injection bottleneck of phosphor-free nanowire white light-emitting diodes. , 2013, Nano letters.

[8]  A. Waag,et al.  Group III nitride core–shell nano‐ and microrods for optoelectronic applications , 2013 .

[9]  T. Unold,et al.  Numerical simulation of cross section electron-beam induced current in thin-film solar-cells for low and high injection conditions , 2013 .

[10]  Simona Podda,et al.  XEBIC at the Dual Beam , 2013, Microelectron. Reliab..

[11]  M. Lu,et al.  Dynamic visualization of axial p-n junctions in single gallium nitride nanorods under electrical bias. , 2013, ACS nano.

[12]  Ping Lu,et al.  Three-dimensional mapping of quantum wells in a GaN/InGaN core-shell nanowire light-emitting diode array. , 2013, Nano letters.

[13]  Mathieu Leroux,et al.  Dependence of the Mg-related acceptor ionization energy with the acceptor concentration in p-type GaN layers grown by molecular beam epitaxy , 2013 .

[14]  A. Waag,et al.  Continuous-Flow MOVPE of Ga-Polar GaN Column Arrays and Core–Shell LED Structures , 2013 .

[15]  Xiaoping Zhou,et al.  Correlation of doping, structure, and carrier dynamics in a single GaN nanorod , 2013 .

[16]  P. Tchoulfian,et al.  High conductivity in Si-doped GaN wires , 2013 .

[17]  H. Tan,et al.  Three-dimensional in situ photocurrent mapping for nanowire photovoltaics. , 2013, Nano letters.

[18]  J. Eymery,et al.  Metal organic vapour-phase epitaxy growth of GaN wires on Si (111) for light-emitting diode applications , 2013, Nanoscale Research Letters.

[19]  S. T. Picraux,et al.  Mapping carrier diffusion in single silicon core-shell nanowires with ultrafast optical microscopy. , 2012, Nano letters.

[20]  A. Yamaguchi,et al.  Comparative study of surface recombination in hexagonal GaN and ZnO surfaces , 2012 .

[21]  K. Jiang,et al.  Direct identification of metallic and semiconducting single-walled carbon nanotubes in scanning electron microscopy. , 2012, Nano letters.

[22]  W. Prost,et al.  Direct determination of minority carrier diffusion lengths at axial GaAs nanowire p-n junctions. , 2012, Nano letters.

[23]  M. Al‐Jassim,et al.  Measurement of semiconductor surface potential using the scanning electron microscope , 2012 .

[24]  Un Jeong Kim,et al.  Nearly single-crystalline GaN light-emitting diodes on amorphous glass substrates , 2011 .

[25]  F. Donatini,et al.  Carrier depletion and exciton diffusion in a single ZnO nanowire , 2011, Nanotechnology.

[26]  J. Eymery,et al.  M-plane core-shell InGaN/GaN multiple-quantum-wells on GaN wires for electroluminescent devices. , 2011, Nano letters.

[27]  H. Morkoç,et al.  Photoluminescence of Mg‐doped m‐plane GaN grown by MOCVD on bulk GaN substrates , 2011 .

[28]  J. Eymery,et al.  Light emitting diodes based on GaN core/ shell wires grown by MOVPE on n-type Si substrate , 2011 .

[29]  A. Castiglia,et al.  Role of stable and metastable Mg-H complexes in p-type GaN for cw blue laser diodes , 2011 .

[30]  K. Crozier,et al.  Dramatic reduction of surface recombination by in situ surface passivation of silicon nanowires. , 2011, Nano letters.

[31]  A. Alec Talin,et al.  Transport imaging for contact-free measurements of minority carrier diffusion in GaN, GaN/AlGaN, and GaN/InGaN core-shell nanowires , 2011 .

[32]  Dong Yu,et al.  Electric field dependent photocurrent decay length in single lead sulfide nanowire field effect transistors. , 2011, Nano letters.

[33]  L. Samuelson,et al.  Diffusion length measurements in axial and radial heterostructured nanowires using cathodoluminescence , 2011 .

[34]  J. Eymery,et al.  Homoepitaxial growth of catalyst-free GaN wires on N-polar substrates , 2010 .

[35]  L. Samuelson,et al.  Determination of diffusion lengths in nanowires using cathodoluminescence , 2010 .

[36]  Z. Barkay,et al.  Secondary electron doping contrast: Theory based on scanning electron microscope and Kelvin probe force microscopy measurements , 2010 .

[37]  J. Eymery,et al.  Self-assembled growth of catalyst-free GaN wires by metal–organic vapour phase epitaxy , 2010, Nanotechnology.

[38]  C. Humphreys,et al.  High resolution dopant profiling in the SEM, image widths and surface band-bending , 2008 .

[39]  Hadis Morko,et al.  Handbook of Nitride Semiconductors and Devices , 2008 .

[40]  Peng Wang,et al.  High-resolution detection of Au catalyst atoms in Si nanowires. , 2008, Nature nanotechnology.

[41]  Nathan S Lewis,et al.  Photovoltaic measurements in single-nanowire silicon solar cells. , 2008, Nano letters.

[42]  P. Russell,et al.  On the use of Monte Carlo modeling in the mathematical analysis of scanning electron microscopy–electron beam induced current data , 2006 .

[43]  L. Lauhon,et al.  Local photocurrent mapping as a probe of contact effects and charge carrier transport in semiconductor nanowire devices , 2006 .

[44]  Charles M. Lieber,et al.  Dopant-free GaN/AlN/AlGaN radial nanowire heterostructures as high electron mobility transistors. , 2006, Nano letters.

[45]  Charles M. Lieber,et al.  Core/multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes. , 2005, Nano letters.

[46]  Naoki Kobayashi,et al.  Minority carrier diffusion length in GaN: Dislocation density and doping concentration dependence , 2018 .

[47]  C. Humphreys,et al.  Mapping the potential within a nanoscale undoped GaAs region using a scanning electron microscope , 2004, cond-mat/0408146.

[48]  P. Russell,et al.  Minority-carrier diffusion length in a GaN-based light-emitting diode , 2001 .

[49]  Eugene E. Haller,et al.  Local vibrational modes of the Mg–H acceptor complex in GaN , 1996 .

[50]  J. Bonard,et al.  Quantitative analysis of electron-beam-induced current profiles across p-n junctions in GaAs/Al0.4Ga0.6As heterostructures , 1996 .

[51]  S. Nakamura,et al.  Highly P-Typed Mg-Doped GaN Films Grown with GaN Buffer Layers , 1991 .

[52]  H. Amano,et al.  P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI) , 1989 .

[53]  J. Eymery,et al.  Single-Wire Light-Emitting Diodes Based on GaN Wires Containing Both Polar and Nonpolar InGaN/GaN Quantum Wells , 2011 .

[54]  Sealy,et al.  Mechanism for secondary electron dopant contrast in the SEM , 2000, Journal of electron microscopy.