Germanium doping of cubic GaN grown by molecular beam epitaxy

We present a study of germanium as an alternative to silicon for n-type doping of cubic GaN. We find that Ge is a well-suited donor impurity. Our layers were grown by plasma-assisted molecular beam epitaxy on 3C-SiC/Si (001) substrates. Germanium-doped layers were fabricated with donor concentrations ranging over several orders of magnitude up to 3.7 × 1020 cm−3. For comparison, silicon-doped layers with donor concentrations of up to 3.8 × 1019 cm−3 were also grown. Incorporation of germanium into the cubic GaN layers was verified by time-of-flight secondary ion mass spectrometry. The crystalline quality of our layers was analyzed using high-resolution x-ray diffraction. Germanium- as well as silicon-doped layers with donor concentrations above 1019 cm−3 exhibited an increase of the dislocation density with increasing dopant concentration. The surface topography of our layers was investigated by atomic force microscopy. Comparable values for the surface roughness were measured for germanium- as well as silicon-doped layers. Optical properties were investigated by photoluminescence spectroscopy at 13 K. Doping with silicon resulted in a spectrally slightly narrower luminescence than doping with germanium. Donor concentrations and carrier mobilities were determined by Hall effect measurements at room temperature and we observe 20% higher electron mobilities for Ge-doping compared to Si-doping in the case of high dopant concentrations.We present a study of germanium as an alternative to silicon for n-type doping of cubic GaN. We find that Ge is a well-suited donor impurity. Our layers were grown by plasma-assisted molecular beam epitaxy on 3C-SiC/Si (001) substrates. Germanium-doped layers were fabricated with donor concentrations ranging over several orders of magnitude up to 3.7 × 1020 cm−3. For comparison, silicon-doped layers with donor concentrations of up to 3.8 × 1019 cm−3 were also grown. Incorporation of germanium into the cubic GaN layers was verified by time-of-flight secondary ion mass spectrometry. The crystalline quality of our layers was analyzed using high-resolution x-ray diffraction. Germanium- as well as silicon-doped layers with donor concentrations above 1019 cm−3 exhibited an increase of the dislocation density with increasing dopant concentration. The surface topography of our layers was investigated by atomic force microscopy. Comparable values for the surface roughness were measured for germanium- as well as si...

[1]  D. Reuter,et al.  Incorporation of germanium for n‐type doping of cubic GaN , 2017 .

[2]  D. Reuter,et al.  Optical Properties of Germanium Doped Cubic GaN , 2017 .

[3]  C. T. Foxon,et al.  Photoluminescence of magnesium and silicon doped cubic GaN , 2014 .

[4]  J. Bläsing,et al.  Ge as a surfactant in metal-organic vapor phase epitaxy growth of a-plane GaN exceeding carrier concentrations of 1020 cm−3 , 2013 .

[5]  M. Albrecht,et al.  Blocking growth by an electrically active subsurface layer: the effect of Si as an antisurfactant in the growth of GaN. , 2013, Physical review letters.

[6]  C. Cobet,et al.  Optical properties of cubic GaN from 1 to 20 eV , 2012 .

[7]  J. Bläsing,et al.  High Si and Ge n-type doping of GaN doping - Limits and impact on stress , 2012 .

[8]  H. Maier,et al.  Anti-phase domains in cubic GaN , 2011 .

[9]  P. De Bièvre,et al.  Atomic weights of the elements. Review 2000 (IUPAC Technical Report) , 2009 .

[10]  K. Lischka,et al.  In situ growth regime characterization of cubic GaN using reflection high energy electron diffraction , 2007, cond-mat/0702018.

[11]  Dieter K. Schroder,et al.  Semiconductor Material and Device Characterization: Schroder/Semiconductor Material and Device Characterization, Third Edition , 2005 .

[12]  C. Walle,et al.  First-principles calculations for defects and impurities: Applications to III-nitrides , 2004 .

[13]  D. As.  n- and p-Type Doping of Cubic GaN , 2002 .

[14]  Klaus Lischka,et al.  p-Type Doping of Cubic GaN by Carbon , 2001 .

[15]  T. Chassagne,et al.  p and n type doping of cubic GaN on SiC (001) , 2001 .

[16]  T. Frauenheim,et al.  Dislocations in hexagonal and cubic GaN , 2000 .

[17]  Yanjun Han,et al.  Influence of Si doping on optical characteristics of cubic GaN grown on (001) GaAs substrates , 2000 .

[18]  C. Walle,et al.  Effect of Si doping on the strain and defect structure of GaN thin films , 1999 .

[19]  Subhasis Ghosh,et al.  Low field electron mobility in GaN , 1999 .

[20]  Ulrike Grossner,et al.  The effect of doping and growth stoichiometry on the core structure of a threading edge dislocation in GaN , 1998 .

[21]  Kiyoshi Takahashi,et al.  High-resolution X-ray diffraction analysis of cubic GaN grown on (0 0 1)GaAs by RF-radical source molecular beam epitaxy , 1998 .

[22]  D. Schikora,et al.  The near band edge photoluminescence of cubic GaN epilayers , 1997 .

[23]  Yang,et al.  Identification of optical transitions in cubic and hexagonal GaN by spatially resolved cathodoluminescence. , 1996, Physical review. B, Condensed matter.

[24]  John E. Ayers,et al.  New model for the thickness and mismatch dependencies of threading dislocation densities in mismatched heteroepitaxial layers. , 1995 .

[25]  Greene,et al.  Temperature-dependent optical band gap of the metastable zinc-blende structure beta -GaN. , 1994, Physical review. B, Condensed matter.

[26]  P. D. Desai.  Thermodynamic Properties of Iron and Silicon , 1986 .

[27]  A. Kelly,et al.  The estimation of dislocation densities in metals from X-ray data , 1953 .

[28]  G. Thomson,et al.  The Antoine equation for vapor-pressure data. , 1946, Chemical reviews.