Resistivity control in unintentionally doped GaN films grown by MOCVD

Abstract The relationship of GaN resistivity to film microstructure and impurity compensation are investigated using transmission electron microscopy, secondary ion mass spectroscopy, X-ray diffraction, and resistance measurements. Unintentionally doped GaN films grown by MOCVD at varying pressures exhibit increased grain size, reduced carbon and oxygen impurity incorporation, reduction in the density of threading dislocations (TDs) with an edge component, and reduced resistivity with increasing growth pressure. Variation in resistivity over eight orders of magnitude is observed as a result of varying the MOCVD growth pressure in a controlled experiment. Our results suggest that disclocations play an important role in the resistivity of GaN. Evidence is presented of impurities segregating at TDs having an edge component, and acting as compensating centers. The control of such compensation as a function of MOCVD growth conditions is outlined.

[1]  Walter Kruppa,et al.  Trapping effects and microwave power performance in AlGaN/GaN HEMTs , 2001 .

[2]  W. Breiland,et al.  Gas-phase nanoparticle formation during AlGaN metalorganic vapor phase epitaxy , 2002 .

[3]  Baoquan Sun,et al.  Formation mechanism of a degenerate thin layer at the interface of a GaN/sapphire system , 2000 .

[4]  X. H. Wu,et al.  Dislocation generation in GaN heteroepitaxy , 1998 .

[5]  J. Northrup,et al.  Screw dislocations in GaN: The Ga-filled core model , 2001 .

[6]  Sven Öberg,et al.  Theory of Threading Edge and Screw Dislocations in GaN , 1997 .

[7]  Daniel D. Koleske,et al.  GaN decomposition in H2 and N2 at MOVPE temperatures and pressures , 2001 .

[8]  Guy Beadie,et al.  Persistent Photoconductivity in n-Type GaN , 1997 .

[9]  Lester F. Eastman,et al.  Scattering of electrons at threading dislocations in GaN , 1998 .

[10]  C. S. Oh,et al.  Conductive layer near the GaN/sapphire interface and its effect on electron transport in unintentionally doped n-type GaN epilayers , 2000 .

[11]  H. Amano,et al.  Growth mechanism of GaN grown on sapphire with A1N buffer layer by MOVPE , 1991 .

[12]  R. Thomas,et al.  Status of device-qualified GaAs substrate technology for GaAs integrated circuits , 1988, Proc. IEEE.

[13]  James S. Speck,et al.  Role of threading dislocation structure on the x‐ray diffraction peak widths in epitaxial GaN films , 1996 .

[14]  A. Wickenden,et al.  Chapter 10 – Structural defects in nitride heteroepitaxy , 2000 .

[15]  David C. Look,et al.  Dislocation Scattering in GaN , 1999 .

[16]  A. Wickenden,et al.  Enhanced GaN decomposition in H2 near atmospheric pressures , 1998 .

[17]  Direct evidence for defect conduction at interface between gallium nitride and sapphire , 2000 .

[18]  Olivier Briot,et al.  Gallium vacancies and the growth stoichiometry of GaN studied by positron annihilation spectroscopy , 1998 .

[19]  Armin Dadgar,et al.  Decoration effects as origin of dislocation-related charges in gallium nitride layers investigated by scanning surface potential microscopy , 2003 .

[20]  J. B. Webb,et al.  Properties of carbon-doped GaN , 2001 .

[21]  J. C. Chen,et al.  Characterization of GaN using thermally stimulated current and photocurrent spectroscopies and its application to UV detectors , 1997 .

[22]  W. J. Moore,et al.  The influence of OMVPE growth pressure on the morphology, compensation, and doping of GaN and related alloys , 2000 .

[23]  Daniel D. Koleske,et al.  Influence of MOVPE growth conditions on carbon and silicon concentrations in GaN , 2002 .

[24]  Isamu Akasaki,et al.  Effects of ain buffer layer on crystallographic structure and on electrical and optical properties of GaN and Ga1−xAlxN (0 < x ≦ 0.4) films grown on sapphire substrate by MOVPE , 1989 .

[25]  S. Binari,et al.  Influence of AlN nucleation layer temperature on GaN electronic properties grown on SiC , 2002 .

[26]  Sven Öberg,et al.  DEEP ACCEPTORS TRAPPED AT THREADING-EDGE DISLOCATIONS IN GAN , 1998 .

[27]  D. Lang,et al.  Nature of the highly conducting interfacial layer in GaN films , 2000 .

[28]  Jaime A. Freitas,et al.  Photoionization spectroscopy of traps in GaN metal-semiconductor field-effect transistors , 2000 .