Schottky diode

Schottky diode
Name	Schottky diode
Type	Semiconductor device
Material	Metal–semiconductor junction
Applications	Power rectification, RF detection, clamping

Schottky diode

Schottky diode is a unipolar semiconductor device formed by a metal–semiconductor junction that yields low forward voltage drop and fast switching. It combines properties exploited in rectification, radio frequency detection, and voltage clamping used across industries and institutions such as General Electric, IBM, Siemens, National Semiconductor, and Texas Instruments. The device is central to power electronics efforts seen in projects at Massachusetts Institute of Technology, Stanford University, Delft University of Technology, Toshiba, and Infineon Technologies.

Introduction

The Schottky diode operates via a rectifying barrier at a metal–semiconductor interface with applications spanning Intel server power supplies, Qualcomm radio front ends, ABB drives, and NASA missions. Seminal industrial adopters include Fairchild Semiconductor, Analog Devices, and ON Semiconductor, while research groups at University of Cambridge, ETH Zurich, and University of California, Berkeley have advanced modeling and materials. Manufacturing and supply chains involve corporations like STMicroelectronics, Renesas Electronics, Micron Technology, Samsung Electronics, and Sony Corporation.

History and development

Early theoretical foundations trace to scientists associated with Bell Labs, Rutherford, and experimentalists in the era of Ernest Rutherford-linked institutions and laboratories such as Bell Telephone Laboratories and facilities at Cambridge University. Industrial development accelerated with contributions from engineers at Western Electric, ITT Corporation, Motorola, and researchers affiliated with Royal Society fellows and awardees of the Nobel Prize in Physics era. The device gained prominence during expansions of computing at IBM and telecommunications at AT&T, and later during consumer electronics booms overseen by firms like Panasonic Corporation and Hitachi. Collaborative efforts across universities including University of Illinois Urbana–Champaign, Imperial College London, and Kyoto University led to improvements in barrier control, with governmental funding from agencies such as DARPA and European Commission influencing commercialization.

Structure and materials

A Schottky diode typically comprises a metal contact deposited on an n-type semiconductor substrate; prominent semiconductor vendors and foundries such as TSMC, GlobalFoundries, SMIC, and Tower Semiconductor have implemented varied stacks including silicon, gallium arsenide, and silicon carbide. Metals used historically and in modern processes include platinum, gold, nickel, and tungsten from suppliers tied to BASF, Corning Incorporated, and Applied Materials. Research on wide-bandgap semiconductors at Northrop Grumman and Raytheon Technologies accelerated use of silicon carbide and gallium nitride for higher-temperature operation; collaborative work with institutions like Caltech and University of Tokyo expanded material choices.

Operating principles

Operation depends on formation of a Schottky barrier whose height and width determine carrier transport; this physics was articulated in contexts studied at Harvard University, Yale University, and Princeton University. Thermionic emission, tunneling, and field emission processes are modeled in work cited by scholars linked to Cornell University and Johns Hopkins University, while device simulation efforts often use tools from vendors such as Cadence Design Systems, Synopsys, and ANSYS. Circuit designers at Apple Inc., Microsoft, and Google exploit the diode's low forward drop and reverse recovery characteristics in power management integrated circuits developed alongside companies like Maxim Integrated and Linear Technology.

Electrical characteristics and performance

Key parameters include forward voltage drop, reverse leakage current, junction capacitance, and breakdown voltage—metrics benchmarked by standards bodies like IEC, JEDEC, and IEEE. Performance improvements have been driven by collaborations among NXP Semiconductors, Dialog Semiconductor, Rohm Semiconductor, and academic groups at Imperial College London and University of Waterloo. Characterization techniques developed at National Institute of Standards and Technology, Fraunhofer Society, and NIST labs quantify switching speed and thermal resistance, guiding selection for applications at Bosch, Siemens Energy, and GE Renewable Energy.

Fabrication and packaging

Fabrication processes for Schottky diodes are implemented in fabs operated by TSMC, Samsung Foundry, Intel Corporation, and GlobalFoundries using equipment from Applied Materials, Lam Research, and KLA Corporation. Packaging formats range from discrete TO-220 and SOD-123 to surface-mount packages used by Broadcom Inc. and Murata Manufacturing, with assembly services by Jabil, Flex Ltd., and Foxconn. Advanced packaging and thermal management draw on expertise from 3M, Corning Incorporated, and Thermalright-affiliated suppliers.

Applications

Schottky diodes are used in power supply rectifiers for servers at Amazon Web Services, in RF mixers for cellular infrastructure by Ericsson and Huawei, in automotive electronics for companies such as Bosch and Delphi Technologies, and in aerospace systems by Boeing and Lockheed Martin. Consumer devices from Samsung Electronics, Apple Inc., and Sony Corporation incorporate Schottky devices in charging circuits, while renewable energy inverters by Siemens Gamesa and Vestas use them for freewheeling and clamping. Medical devices produced by Medtronic and Philips employ Schottky-based rectification in imaging and monitoring equipment.

Reliability and limitations

Limitations include higher reverse leakage and lower breakdown voltage compared with p–n diodes—issues studied at Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, and Sandia National Laboratories. Reliability testing protocols from JEDEC and UL inform use in safety-critical systems designed by Honeywell and Rolls-Royce Holdings. Mitigation strategies developed through collaborations between ABB and academic partners at KTH Royal Institute of Technology involve thermal management, barrier engineering, and packaging choices to address electromigration and thermal runaway concerns.

Category:Semiconductor diodes