About

Srabanti Chowdhury is a Professor of Electrical Engineering and a Senior Fellow at the Precourt Institute for Energy at Stanford University. She holds a courtesy appointment in Materials Science and Engineering. Her research focuses on electrical engineering with an emphasis on energy-related applications, contributing to the development of advanced materials and systems for energy efficiency and sustainability. As a senior fellow at the Precourt Institute for Energy, her work integrates electrical engineering principles with energy science to address critical challenges in energy storage, conversion, and management.

Research topics

• Materials science
• Computer Science
• Optoelectronics
• Electrical engineering
• Engineering
• Engineering physics
• Nanotechnology
• Physics
• Electronic engineering
• Acoustics
• Telecommunications
• Composite material

Selected publications

• Heavy‐Ion Irradiation Response of Gallium Nitride High‐Electron‐Mobility Transistors with Reduced Surface Field Technology

  physica status solidi (a) · 2026-01-01

  articleSenior authorCorresponding

  In space, semiconductor technologies face significant reliability challenges due to cosmic radiation, necessitating novel materials for enhanced radiation resistance. Gallium nitride high‐electron‐mobility transistors (GaN HEMTs) offer improved low‐energy irradiation reliability over conventional semiconductors but struggle with single‐event burnout under high‐energy irradiation, leading to catastrophic failure, primarily due to the high electric fields in the drain region and charge injection effects that trigger breakdown. In this study, a GaN HEMT with reduced surface field technology was designed and fabricated on a semi‐insulating bulk substrate to investigate its high‐energy radiation response. After irradiation under 1713 MeV Au ions (linear energy transfer of 75 MeV cm 2 mg −1 in silicon), two failure mechanisms were identified: source–drain and gate–drain leakage. Additionally, single‐event leakage current was identified in a surviving GaN HEMT.

  PublisherDOI

• Optimization Factors for the Thermal Design of Packaged GaN High-Electron-Mobility Transistors

  IEEE Transactions on Electron Devices · 2026-03-06

  article

  In this work, the junction-to-heat sink thermal resistance (R<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{\text {th}}\text {)}$</tex-math> </inline-formula> of single-finger GaN high-electron-mobility transistors (HEMTs) mounted on a high-power laminate CuMo base package was analyzed using micro-Raman thermometry and electrothermal modeling. Analysis of the internal temperature distribution reveals that the die-attach material, substrate, and the semi-insulating buffer layer, respectively, comprise 2%, 28%, and 63% of the total R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of a packaged device. To reduce the R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of the device, the use of a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\kappa }$</tex-math> </inline-formula> (22 W/m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\cdot } $</tex-math> </inline-formula>K) silver epoxy or AuSn solder (57 W/m<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\cdot }$</tex-math> </inline-formula>K) as the die-attach material is recommended. Simulation results indicate that replacing the substrate with single-crystal diamond lowers R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> by 21%, compared to a standard GaN-on-SiC HEMT. Regarding buffer engineering, a thinner semi-insulating GaN buffer layer leads to a reduced R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> under a fully open channel bias condition. In contrast, under a partially pinched-off bias condition, reducing the thickness of the buffer layer from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.8~\boldsymbol {\mu }$</tex-math> </inline-formula>m to 400 nm leads to a ~10% increase in peak channel temperature rise. This finding was confirmed by performing nanoparticle-assisted Raman thermometry on transfer length method (TLM) structures with varying channel lengths, which demonstrated that buffer layer thickness optimization must account for the heat flux distribution and device geometry. Simulation results show that deposition of a polycrystalline (PC) diamond top-side heat spreader can lower R<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of a GaN-on-SiC HEMT by 17%. The findings of this work provide insight into the thermal design optimization of GaN monolithic microwave integrated circuits (MMICs).

  PublisherDOI

• Diffusion-driven formation of current blocking layers in GaN using Mg-doped spin-on glass-based technique

  Journal of Applied Physics · 2026-05-11

  articleOpen accessSenior author

  This work reports the first demonstration of magnesium (Mg)-doped spin-on-glass based diffusion to achieve selective-area current-blocking layers in gallium nitride (GaN). We employed an oxygen-assisted annealing process to facilitate Mg diffusion into GaN. The optimized diffusion process enabled Mg concentration profiles exceeding 1 × 1019 cm−3 at depths beyond 200 nm. Diodes fabricated using this method exhibited enhanced blocking capabilities, increasing from under 30 V (in reference Schottky barrier diodes) to 200–400 V, depending on the annealing conditions. Devices annealed at 1050 °C demonstrated specific on-resistances of 7.3 mΩ cm2, comparable to the 3 mΩ cm2 observed in reference Schottky barrier diodes. In contrast, when the annealing was performed in N2 instead of an O2 ambient, Mg-diffused layers exhibited similar Mg concentrations and breakdown voltages to reference Schottky barrier diodes that did not go through the Mg diffusion process. These findings highlight the potential of oxygen-assisted two-step annealing as a viable technique for enabling Mg diffusion and forming effective current-blocking layers in GaN-based devices.

  PublisherOA PDFDOI

• Cooling performance of top-side polycrystalline diamond integration in RF-power N-polar GaN high-electron-mobility transistors predicted using a robust modeling platform

  Journal of Applied Physics · 2026-03-17 · 1 citations

  articleOpen accessSenior author

  This study evaluates the cooling performance of top-side polycrystalline diamond (PCD) integration as an advanced thermal management strategy for N-polar GaN high-electron-mobility transistors (HEMTs) in high-power and radio-frequency (RF) electronics, using technology computer-aided design (TCAD). We constructed a robust mobility model based on well-established scattering theory and incorporated it into our device simulations, allowing reliable characterization of thermal effects and accurate projection of device performance under extreme conditions such as high temperatures and high electric fields. Large-signal power-sweep simulations of 70-nm GaN HEMTs integrated with a 500-nm PCD layer, operating at 94 GHz with applied voltages up to 20 V and bias currents of approximately 650 mA/mm, reveal a peak temperature reduction of 33%. The applied thermal management enables an increase of 39% in output power (Pout), 38% in power gain (GT), together with a 76% improvement in power-added efficiency (PAE). Our findings also reveal a superlinear increase in peak temperature with dissipated power, governed by the local electric field at the hotspot and the channel conductance. This behavior provides new physical insights into heat generation and thermal transport in GaN HEMTs.

  PublisherDOI

• Diamond Blankets Will Chill Future Chips: A Micrometers-Thick Integrated Layer Spreads Out the Heat

  IEEE Spectrum · 2025-11-01

  article1st authorCorresponding

  Today's stunning computing power is allowing us to move from human intelligence toward artificial intelligence. And as our machines gain more power, they're becoming not just tools but decision-makers shaping our future.

  PublisherDOI

• How Cool is Diamond? for Heat Extraction and Integration

  2025-06-22

  article1st authorCorresponding

  The continuous drive for higher power density in computing, RF electronics, and high-performance systems necessitates innovative thermal management strategies. While advances in chip packaging have improved heat dissipation, fundamental challenges remain due to obstructed heat pathways created by multiple material layers and low-conductivity dielectric stacks. Conventional cooling methods often fail to efficiently extract heat from within these complex architectures, limiting both device performance and longterm reliability.

  PublisherDOI

• Exploring the performance of GaN trench CAVETs from cryogenic to elevated temperatures

  Frontiers in Electronics · 2025-08-12 · 2 citations

  articleOpen accessSenior authorCorresponding

  Fabricated GaN trench current aperture vertical electron transistors (CAVETs) were characterized across a wide temperature range for the first time, including in situ cryogenic measurements down to 10 K and ex situ thermal shock testing at elevated temperatures of 773 K and 1073 K. The device featured a highly conductive AlGaN/GaN channel regrown on p-GaN following trench etching. As the temperature decreased, the field-effect mobility in the regrown two-dimensional electron gas (2DEG) channel increased from 1886 cm 2 /(V∙s) at 296 K to 3577 cm 2 /(V∙s) at 10 K. The device maintained a stable threshold voltage (V TH ). The subthreshold slope (SS) decreased from 98.32 mV/dec to 51.31 mV/dec, and the I on /I off ratio increased from 3 × 10 9 to 9 × 10 10 over the same temperature range. The specific on-state resistance (R on,sp ) decreased from 1.02 mΩ cm 2 at 296 K to 0.586 mΩ cm 2 at 10 K. Furthermore, 1-min thermal shock testing was conducted as a preliminary method to assess the resilience of trench CAVET at elevated temperatures. The device maintained field effect transistor (FET) functionality after exposure to 773 K, albeit with reduced current. Testing at 1073 K resulted in more significant performance degradation, including a sharp increase in R on,sp and failure to achieve pinch-off due to a pronounced surge in gate leakage.

  PublisherOA PDFDOI

• Physical modeling and design of a non-volatile optically gated high-power diamond transistor

  2025-08-19

  articleOpen access

  In this work, we present the theory of an optically gated diamond-based junction field-effect transistor implemented on a type Ib diamond substrate with deep nitrogen donor-like traps and a boron-doped epi-layer on top. Using sub-gap lasers with intensities as low as 10 W/cm 2 , electrons are optically excited from the nitrogen traps to the conduction band of the diamond substrate, thus enabling the back gate to exercise an efficient control on modulating the space-charge region at the junction and therefore the channel conductivity. We show that the device can deliver a current of 7 µA/µm, or equivalently 1750 A/cm 2 , while switching at a frequency greater than 2 kHz, in a form factor of 5 µm 2. The breakdown voltage is found to be greater than 1850 V, with a breakdown field strength of ∼11 MV/cm. Moreover, the device supports non-volatile operation for higher immunity to electromagnetic interference. Early experimental results conducted in an unoptimized device structure are in excellent agreement with the model, while more advanced experimental studies, driven by the predictive model, are currently underway.

  PublisherOA PDFDOI

• Systematic investigation of AlGaN channels on AlN/sapphire substrates using metal–organic chemical vapor deposition (MOCVD): Toward higher crystallinity and lower surface roughness

  APL Materials · 2025-05-01 · 3 citations

  articleOpen accessSenior author

  Aluminum nitride (AlN) stands out as a wide bandgap semiconductor due to its exceptional combination of high thermal conductivity and high electrical resistivity, a rare pairing that makes it uniquely suited for advanced electronic applications. In addition, its unique ability to support the growth of high-Al-content AlGaN enables power electronic devices, including high electron mobility transistors (HEMTs) and diodes, to surpass the performance limits of conventional GaN-channel HEMTs. However, the influence of Al composition on the electronic band structure of AlGaN channel HEMTs remains insufficiently explored, particularly for structures grown via metalorganic chemical vapor deposition. In this study, a high-quality AlN-on-sapphire platform is established as the foundation for subsequent growth. A series of AlxGa1−xN/AlN heterostructures were grown on this platform, with the Al composition x systematically varied between 0 and 0.70. For x = 0 (GaN), a 2DEG density of 3.49 × 1013 cm−2 was observed. As x increased, the 2DEG density slightly decreased; however, most compositions maintained 2DEG densities above 1 × 1013 cm−2. Both sheet resistance and Hall mobility exhibited a clear dependence on the Al composition, with Hall mobility increasing as x decreased. These findings provide valuable insights into the interplay between Al composition and transport properties in AlGaN/AlN heterostructures, further informing their potential for high power electronic applications.

  PublisherDOI

• Structural and chemical transitions in diamond/dielectric/Si heterostructures

  Acta Materialia · 2025-04-07

  article
  PublisherDOI

Recent grants

• CAREER: A New GaN-based Unit Cell for Highly Efficient Integrated Power Conversion

  NSF · $394k · 2016–2020

Frequent coauthors

• Samuel Graham

  University of Maryland, College Park

  43 shared

• Marko J. Tadjer

  United States Naval Research Laboratory

  42 shared

• Sukwon Choi

  Pennsylvania State University

  40 shared

• Eric R. Heller

  United States Air Force Research Laboratory

  38 shared

• Mohamadali Malakoutian

  37 shared

• Gilberto Moreno

  National Renewable Energy Laboratory

  36 shared

• Sreekant Narumanchi

  National Renewable Energy Laboratory

  36 shared

• Dong Ji

  Chinese University of Hong Kong, Shenzhen

  30 shared

Awards & honors

• 2023 Technical Excellence Award from the Semiconductor Resea…
• 2025 Quantum Device Award for contribution to Vertical GaN d…
• 2020 Alfred P. Sloan Fellowship in Physics
• 2016 Young Scientist Award at the International Symposium on…
• DARPA Young Faculty Award (2015)