The Doping Dependence of the Thermal Conductivity of Bulk Gallium Nitride Substrates

Gallium nitride (GaN) has emerged as one of the most attractive base materials for next-generation high-power and high-frequency electronic devices. Recent efforts have focused on realizing vertical power device structures such as in situ oxide, GaN interlayer based vertical trench metal–oxide–semiconductor field-effect transistors (OG-FETs). Unfortunately, the higher-power density of GaN electronics inevitably leads to considerable device self-heating which impacts device performance and reliability. Halide vapor-phase epitaxy (HVPE) is currently the most common approach for manufacturing commercial GaN substrates used to build vertical GaN transistors. Vertical device structures consist of GaN layers of diverse doping levels. Hence, it is of crucial importance to measure and understand how the dopant type (Si, Fe, and Mg), doping level, and crystal quality alter the thermal conductivity of HVPE-grown bulk GaN. In this work, a steady-state thermoreflectance (SSTR) technique was used to measure the thermal conductivity of HVPE-grown GaN substrates employing different doping schemes and levels. Structural and electrical characterization methods including X-ray diffraction (XRD), secondary-ion mass spectrometry (SIMS), Raman spectroscopy, and Hall-effect measurements were used to determine and compare the GaN crystal quality, dislocation density, doping level, and carrier concentration. Using this comprehensive suite of characterization methods, the interrelation among structural/electrical parameters and the thermal conductivity of bulk GaN substrates was investigated. While doping is evidenced to reduce the GaN thermal conductivity, the highest thermal conductivity (201 W/mK) is observed in a heavily Si-doped (1–5.00 × 1018 cm−3) substrate with the highest crystalline quality. This suggests that phonon-dislocation scattering dominates over phonon-impurity scattering in the tested HVPE-grown bulk GaN substrates. The results provide useful information for designing thermal management solutions for vertical GaN power electronic devices.

[1]  T. Beechem,et al.  Nanoscale electro-thermal interactions in AlGaN/GaN high electron mobility transistors , 2020, Journal of Applied Physics.

[2]  A. Allerman,et al.  Integrated Optical Probing of the Thermal Dynamics of Wide Bandgap Power Electronics , 2019, ASME 2019 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems.

[3]  J. Kwak,et al.  Thermal Management and Characterization of High-Power Wide-Bandgap Semiconductor Electronic and Photonic Devices in Automotive Applications , 2019, Journal of Electronic Packaging.

[4]  Tae Kyoung Kim,et al.  Enhancement of the Electrical and Thermal Performance of AlGaN/GaN HEMTs Using a Novel Resistive Field Plate Structure , 2019, 2019 18th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm).

[5]  E. Pop,et al.  Thermal conductivity of crystalline AlN and the influence of atomic-scale defects , 2019, Journal of Applied Physics.

[6]  P. Hopkins,et al.  A steady-state thermoreflectance method to measure thermal conductivity. , 2019, The Review of scientific instruments.

[7]  G. Tränkle,et al.  Influence of quartz on silicon incorporation in HVPE grown AlN , 2019, Journal of Crystal Growth.

[8]  M. Boćkowski,et al.  Thermal conductivity of GaN single crystals: Influence of impurities incorporated in different growth processes , 2018, Journal of Applied Physics.

[9]  D. Ji,et al.  Switching performance analysis of GaN OG-FET using TCAD device-circuit-integrated model , 2018, 2018 IEEE 30th International Symposium on Power Semiconductor Devices and ICs (ISPSD).

[10]  P. Hopkins,et al.  On the steady-state temperature rise during laser heating of multilayer thin films in optical pump-probe techniques , 2018 .

[11]  M. Boćkowski,et al.  Crystal growth of HVPE-GaN doped with germanium , 2017 .

[12]  Umesh K. Mishra,et al.  Demonstrating >1.4 kV OG-FET performance with a novel double field-plated geometry and the successful scaling of large-area devices , 2017, 2017 IEEE International Electron Devices Meeting (IEDM).

[13]  F. Horikiri,et al.  Hydride-vapor-phase epitaxial growth of highly pure GaN layers with smooth as-grown surfaces on freestanding GaN substrates , 2017 .

[14]  H. Kim,et al.  Electro-thermal reliability study of GaN high electron mobility transistors , 2017, 2017 16th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm).

[15]  Theodore D. Moustakas,et al.  Thickness dependent thermal conductivity of gallium nitride , 2017 .

[16]  Martin Kuball,et al.  A Review of Raman Thermography for Electronic and Opto-Electronic Device Measurement With Submicron Spatial and Nanosecond Temporal Resolution , 2016, IEEE Transactions on Device and Materials Reliability.

[17]  U. Mishra,et al.  OG-FET: An In-Situ ${O}$ xide, ${G}$ aN Interlayer-Based Vertical Trench MOSFET , 2016, IEEE Electron Device Letters.

[18]  Christina M. Rost,et al.  Size dictated thermal conductivity of GaN , 2016 .

[19]  Bradley D. Christiansen,et al.  Benefits of Considering More than Temperature Acceleration for GaN HEMT Life Testing , 2016 .

[20]  Thomas L. Bougher,et al.  Thermal Boundary Resistance in GaN Films Measured by Time Domain Thermoreflectance with Robust Monte Carlo Uncertainty Estimation , 2016 .

[21]  T. Moustakas,et al.  Thermal transport through GaN–SiC interfaces from 300 to 600 K , 2015 .

[22]  D. Bour,et al.  Vertical Power p-n Diodes Based on Bulk GaN , 2015, IEEE Transactions on Electron Devices.

[23]  Chia-Yu Chen,et al.  Activation energy of drain-current degradation in GaN HEMTs under high-power DC stress , 2014, Microelectron. Reliab..

[24]  Roland B. Simon,et al.  Thermal conductivity of bulk GaN—Effects of oxygen, magnesium doping, and strain field compensation , 2014 .

[25]  Yiyang Li,et al.  Phonon scattering in strained transition layers for GaN heteroepitaxy , 2014 .

[26]  R. Vetury,et al.  Thermometry of AlGaN/GaN HEMTs Using Multispectral Raman Features , 2013, IEEE Transactions on Electron Devices.

[27]  Samuel Graham,et al.  Analysis of the residual stress distribution in AlGaN/GaN high electron mobility transistors , 2013 .

[28]  A. Schmidt,et al.  A frequency-domain thermoreflectance method for the characterization of thermal properties. , 2009, The Review of scientific instruments.

[29]  R. Vetury,et al.  Reliability assessment of AlGaN/GaN HEMT technology on SiC for 48V applications , 2008, 2008 IEEE International Reliability Physics Symposium.

[30]  T. Beechem,et al.  Micro-Raman thermometry in the presence of complex stresses in GaN devices , 2008 .

[31]  Michal Bockowski,et al.  Bulk growth of gallium nitride: challenges and difficulties , 2007 .

[32]  John F. Muth,et al.  Accurate dependence of gallium nitride thermal conductivity on dislocation density , 2006 .

[33]  Sang-Jun Cho,et al.  Thermal conductivity of bulk ZnO after different thermal treatments , 2006 .

[34]  S. Keller,et al.  High-power AlGaN/GaN HEMTs for Ka-band applications , 2005, IEEE Electron Device Letters.

[35]  D. Cahill.  Analysis of heat flow in layered structures for time-domain thermoreflectance , 2004 .

[36]  K. H. Ploog,et al.  X-ray diffraction peak profiles from threading dislocations in GaN epitaxial films , 2004, cond-mat/0410510.

[37]  S. Xu,et al.  The depth-profiled carrier concentration and scattering mechanism in undoped GaN film grown on sapphire , 2004 .

[38]  P. Waltereit,et al.  Power performance of AlGaN-GaN HEMTs grown on SiC by plasma-assisted MBE , 2004, IEEE Electron Device Letters.

[39]  J. Gale,et al.  Towards chemical identification in atomic-resolution noncontact afm imaging with silicon tips , 2003 .

[40]  T. Paszkiewicz,et al.  Thermal conductivity of GaN crystals grown by high pressure method , 2003 .

[41]  C. Walle.  Effects of impurities on the lattice parameters of GaN , 2003 .

[42]  James S. Speck,et al.  Correlated scanning Kelvin probe and conductive atomic force microscopy studies of dislocations in gallium nitride , 2003 .

[43]  S. Einfeldt,et al.  Microstructure of heteroepitaxial GaN revealed by x-ray diffraction , 2003 .

[44]  A. Majumdar,et al.  Nanoscale thermal transport , 2003, Journal of Applied Physics.

[45]  T. Kazior,et al.  Trapping effects in GaN and SiC microwave FETs , 2002, Proc. IEEE.

[46]  Alexander A. Balandin,et al.  Thermal conductivity of GaN films: Effects of impurities and dislocations , 2002 .

[47]  James S. Speck,et al.  Direct imaging of reverse-bias leakage through pure screw dislocations in GaN films grown by molecular beam epitaxy on GaN templates , 2002 .

[48]  A. Balandin,et al.  Effect of dislocations on thermal conductivity of GaN layers , 2001 .

[49]  M. Kuball,et al.  Raman spectroscopy of GaN, AlGaN and AlN for process and growth monitoring/control , 2001 .

[50]  C. Gaquiere,et al.  Current instabilities in GaN-based devices , 2001, IEEE Electron Device Letters.

[51]  Sven Einfeldt,et al.  X-ray diffraction analysis of the defect structure in epitaxial GaN , 2000 .

[52]  S. Denbaars,et al.  Heavy doping effects in Mg-doped GaN , 2000 .

[53]  S. Denbaars,et al.  Thermal conductivity of lateral epitaxial overgrown GaN films , 1999 .

[54]  S. Einfeldt,et al.  Analysis of the Defect Structure of Epitaxial GaN , 1999 .

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

[56]  K. Hiramatsu,et al.  Hole trap levels in Mg-doped GaN grown by metalorganic vapor phase epitaxy , 1998 .

[57]  A. Witek,et al.  Some aspects of thermal conductivity of isotopically pure diamond—a comparison with nitrides , 1998 .

[58]  Oliver Ambacher,et al.  Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry , 1998 .

[59]  H. Amano,et al.  Heteroepitaxy of Group III Nitrides for Device Applications , 1997 .

[60]  D. Clarke,et al.  MOSAIC STRUCTURE IN EPITAXIAL THIN FILMS HAVING LARGE LATTICE MISMATCH , 1997 .

[61]  Fernando Ponce,et al.  Direct imaging of impurity-induced Raman scattering in GaN , 1996 .

[62]  Sukwon Choi,et al.  The Impact of Bias Conditions on Self-Heating in AlGaN/GaN HEMTs , 2013, IEEE Transactions on Electron Devices.

[63]  Ming Su,et al.  Challenges in the Automotive Application of GaN Power Switching Devices , 2011 .

[64]  B. G. Mulimani,et al.  Thermal conductivity of GaN , 2007 .

[65]  R. Nemanich,et al.  Raman Spectroscopy for Characterization of Hard, Wide-Bandgap Semiconductors: Diamond, GaN, GaAlN, AlN, BN , 1996 .