About

Manijeh Razeghi is the Walter P. Murphy Professor of Electrical and Computer Engineering at Northwestern University and serves as the Director of the Center for Quantum Devices. Her research focuses on compound quantum semiconductor science and nanotechnology, with an emphasis on developing understanding and advanced semiconductor quantum devices such as lasers, photodetectors, transistors, waveguides, and switches. Her work involves a multidisciplinary approach combining solid state physics, quantum mechanics, electrical, mechanical, and chemical engineering, as well as materials science, often in collaboration with industry, academia, and government agencies. Since its founding in 1992, the Center for Quantum Devices has evolved into a world-class research laboratory under her leadership, achieving numerous scientific breakthroughs and maintaining a leading position in the field. Her contributions include pioneering research in ultraviolet and visible devices based on III-Nitride semiconductors, high-power lasers, infrared quantum cascade lasers, quantum well infrared photodetectors, and nanotechnology using electron-beam lithography. Her work has resulted in extensive publications, patents, and recognition awards, establishing her as a prominent figure in the advancement of semiconductor quantum device technology.

Research topics

• Optics
• Optoelectronics
• Physics
• Materials science

Selected publications

• Self powered oxide heterojunctions for remote optical fire sensing

  2025-03-19

  articleSenior author

  Uncontrolled fires are estimated to contribute as much to carbon gas emissions as all of commercial transport. A key problem is that these fires are often not detected in time to limit the damage because most commercial fire/smoke detectors usually do not go off until it is too late to intervene and quell the conflagration before it takes hold. Remote optical sensing should be a big part of the solution. Although infrared (IR) sensors are the conventional solution for heat detection, they are not ideal for remote optical fire detection because they are subject to multiple confounding signals. For this reason, there is a need for ultraviolet C band (UVC) flame sensors, which are not subject to such false positives because their photoresponse is solar blind. This talk will explore the use of Ga2O3/NiO heterojunctions for use as self-powered remote fire/flame sensors.

  PublisherDOI

• Midinfrared Semiconductor Photonics – A Roadmap

  2025-11-17

  article

  <p dir="ltr">Semiconductor photonic devices operating in the midwave infrared (mid-IR, which we roughly define here as wavelengths spanning 3 to 14 µm) uniquely address a wide range of current practical needs. These include chemical sensing, environmental monitoring, industrial process control, medical diagnostics, thermal imaging, LIDAR, free space optical communication, and security monitoring. However, mid-IR device technologies are currently still works in progress that are generally much less mature than their near infrared and visible counterparts. Not only are most of the relevant materials more difficult to grow and process, but attainment of the desired optical device performance is often fundamentally more challenging. This Roadmap will review the leading applications for mid-IR optoelectronics, summarize the status and deficiencies of current device technologies, and then suggest possible roadmaps for improving and maturing the performance, manufacturability, and cost of each device type so the critical needs that are uniquely addressed by mid-IR photonics can be satisfied.</p>

  PublisherDOI

• Room Temperature Terahertz and Frequency Combs Based on Intersubband Quantum Cascade Laser Diodes: History and Future

  Photonics · 2025-01-17 · 2 citations

  articleOpen access1st authorCorresponding

  The year 2024 marks the 30-year anniversary of the quantum cascade laser (QCL), which is becoming the leading laser source in the mid-infrared (mid-IR) range. Since the first demonstration, QCL has undergone tremendous development in terms of the output power, wall plug efficiency, spectral coverage, wavelength tunability, and beam quality. Owing to its unique intersubband transition and fast gain features, QCL possesses strong nonlinearities that makes it an ideal platform for nonlinear photonics like terahertz (THz) difference frequency generation and direct frequency comb generation via four-wave mixing when group velocity dispersion is engineered. The feature of broadband, high-power, and low-phase noise of QCL combs is revolutionizing mid-IR spectroscopy and sensing by offering a new tool measuring multi-channel molecules simultaneously in the μs time scale. While THz QCL difference frequency generation is becoming the only semiconductor light source covering 1–5 THz at room temperature. In this paper, we will introduce the latest research from the Center for Quantum Devices at Northwestern University and briefly discuss the history of QCL, recent progress, and future perspective of QCL research, especially for QCL frequency combs, room temperature THz QCL difference frequency generation, and major challenges facing QCL in the future.

  PublisherOA PDFDOI

• Room temperature operation of Ge/Si <i>x</i> Ge1− <i>x</i> − <i>y</i> Sn <i>y</i> terahertz quantum cascade lasers predicted using extended combined resonant tunneling and rate equation model

  Journal of Applied Physics · 2025-12-15

  articleOpen access

  Raising operation temperature of terahertz (THz) quantum cascade lasers (QCLs) to room temperature remains a key challenge in QCL community. Group-IV semiconductors are believed to be a promising solution to this problem since the polar phonon–electron scattering is negligible at elevated temperature. Here, we develop a theoretical model for Ge/SixGe1−x−ySny THz QCL development. This model is established on the combined resonant tunneling and rate equation framework and is extended to be applicable for group-IV QCL design through introducing new scattering mechanisms and continuum states carrier leakage. A two-well Ge/Si0.3Ge0.618Sn0.082 THz QCL based on a direct phonon extraction strategy is designed and predicted to be capable of working above 300 K. This result lays the foundation for future room temperature THz QCL devices development using group-IV semiconductors.

  PublisherOA PDFDOI

• High-power, high-wall-plug-efficiency quantum cascade lasers with high-brightness in continuous wave operation at 3–300μm

  Light Science & Applications · 2025-07-25 · 13 citations

  reviewOpen access1st authorCorresponding

  Quantum cascade lasers (QCLs) are unipolar quantum devices based on inter-sub-band transitions. They break the electron-hole recombination mechanism in traditional semiconductor lasers, overcome the long-lasting bottleneck which is that the emission wavelength of semiconductor laser is completely dependent on the bandgap of semiconductor materials. Therefore, their emission wavelength is able to cover the mid-infrared (mid-IR) range and the "Terahertz gap" that is previously inaccessible by any other semiconductor lasers. After thirty years development, QCLs have become the most promising light source in the mid-IR and THz regime. In this paper, we are going to present the strategies and methodologies to achieve high-power, high-wall-plug-efficiency (WPE) QCLs with high-brightness in room temperature continuous-wave (cw) operation at 3-300 μm. We will also review the recent breakthroughs in QCL community, especially the high-power, high WPE intersubband lasers in room temperature cw operation.

  PublisherOA PDFDOI

• Manijeh Razeghi: The curious life of communication physics

  Research outreach · 2024-01-01

  articleOpen access1st authorCorresponding
  PublisherDOI

• MOCVD-grown Ga2O3 thin films for polarization-sensitive infrared photonics

  APL Materials · 2024-01-01 · 1 citations

  articleOpen access

  The phonon modes of materials contain critical information on the quality of the crystals. Phonon modes also offer a wide range of polarization-dependent resonances in infrared that can be tailored to applications that require large dielectric function contrast in different crystal directions. Here, we investigate the far-field characteristics of MOCVD-grown Ga2O3 thin films. With a combination of cross-polarization FTIR and AFM characterization techniques, we propose an easy and non-invasive route to distinguish κ and β phases of Ga2O3 and study the quality of these crystals. Using numerical methods and cross-polarization spectroscopy, the depolarization characteristics of β-Ga2O3 are examined and depolarization strength values as high as 0.495 and 0.76 are measured, respectively, for 400 and 800 nm-thick β-Ga2O3. The strong birefringence near optical phonon modes of an 800 nm β-Ga2O3 on a sapphire substrate is used to obtain several polarization states for the reflected light in the second atmospheric window 8–14 µm. We anticipate that our findings open a new path for material characterization and wave plate design for the mid-IR range and offer novel possibilities for the future of IR on-chip photonics, thanks to the compatibility of β-Ga2O3 with standard nanofabrication technology.

  PublisherOA PDFDOI

• How to achieve high-power room-temperature, continuous wave operation, semiconductor THz laser diodes

  2024-03-12

  article1st authorCorresponding

  This talk will present the world first results related to a compact, high power, room temperature continuous wave terahertz semiconductor laser diodes emitting in a wide frequency range (1-5 THz) based on intracavity difference frequency generation.

  PublisherDOI

• Combined resonant tunneling and rate equation modeling of terahertz quantum cascade lasers

  Journal of Applied Physics · 2024-03-18 · 11 citations

  articleOpen access

  Terahertz (THz) quantum cascade lasers (QCLs) are technologically important laser sources for the THz range but are complex to model. An efficient extended rate equation model is developed here by incorporating the resonant tunneling mechanism from the density matrix formalism, which permits to simulate THz QCLs with thick carrier injection barriers within the semi-classical formalism. A self-consistent solution is obtained by iteratively solving the Schrödinger–Poisson equation with this transport model. Carrier–light coupling is also included to simulate the current behavior arising from stimulated emission. As a quasi-ab initio model, intermediate parameters, such as pure dephasing time and optical linewidth, are dynamically calculated in the convergence process, and the only fitting parameters are the interface roughness correlation length and height. Good agreement has been achieved by comparing the simulation results of various designs with experiments, and other models such as density matrix Monte Carlo and non-equilibrium Green's function method that, unlike here, require important computational resources. The accuracy, compatibility, and computational efficiency of our model enable many application scenarios, such as design optimization and quantitative insights into THz QCLs. Finally, the source code of the model is also provided in the supplementary material of this article for readers to repeat the results presented here, investigate, and optimize new designs.

  PublisherOA PDFDOI

• III-Nitride/Ga2O3 heterostructure for future power electronics: opportunity and challenges

  2024-03-08 · 1 citations

  articleSenior author

  Ga₂O₃ has become the new focal point of high-power semiconductor device research due to its superior capability to handle high voltages in smaller dimensions and with higher efficiencies compared to other commercialized semiconductors. However, the low thermal conductivity of the material is expected to limit device performance. To compensate for the low thermal conductivity of Ga₂O₃ and to achieve a very high density 2-dimensional electron gas (2DEG), an innovative idea is to combine Ga₂O₃ with III-Nitrides (which have higher thermal conductivity), such as AlN. However, metal-polar AlN/&beta;-Ga₂O₃ heterojunction provide type-II heterojunction which are beneficial for optoelectronic application. because of the negative value of specific charge density. On the other hand, N-polar AlN/&beta;-Ga₂O₃ heterostructures provide higher 2DEG concentration and larger breakdown voltage compared to conventional AlGaN/GaN devices. This advancement would allow the demonstration of RF power transistors with a 10x increase in power density compared to today’s State of the Art (SoA) and provide a solution to size, weight, and power-constrained applications.

  PublisherDOI

Recent grants

• Tunable Continuous Wave THz Source Based on a Room Temperature Quantum Cascade Laser

  NSF · $359k · 2013–2016

• Room temperature high-power terahertz semiconductor laser with high-quality beam shape and stable spectral emission

  NSF · $456k · 2022–2025

• Diffraction-grating coupled surface emitting Terahertz quantum cascade laser source for high power, room temperature continuous wave operation

  NSF · $400k · 2016–2019

• Terahertz source frequency comb based on difference frequency generation from a mid-IR quantum cascade laser

  NSF · $360k · 2015–2018

• EAGER: MOCVD Growth of beta-(Al,In,Ga)2O3 for Transistor Applications

  NSF · $150k · 2017–2019

Frequent coauthors

• S. Slivken

  308 shared

• Ryan McClintock

  Northwestern University

  223 shared

• Patrick Kung

  University of Alabama

  180 shared

• Donghai Wu

  159 shared

• Arash Dehzangi

  129 shared

• Abbas Haddadi

  Banpil Photonics (United States)

  110 shared

• C. Bayram

  University of Illinois Urbana-Champaign

  105 shared

• S. R. Darvish

  Helmut Schmidt University

  101 shared

Labs

• Center for Quantum DevicesPI

Awards & honors

• 152 prestigious recognition awards