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Solar-Blind Deep UV AlGaN Based Aval...

Gautam, Lakshay.

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Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection./
Author:	Gautam, Lakshay.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2024,
Description:	161 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-10, Section: B.
Contained By:	Dissertations Abstracts International85-10B.
Subject:	Electrical engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30820281
ISBN:	9798381976748

Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection.
Gautam, Lakshay.

Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection. - Ann Arbor : ProQuest Dissertations & Theses, 2024 - 161 p.

Source: Dissertations Abstracts International, Volume: 85-10, Section: B.

Thesis (Ph.D.)--Northwestern University, 2024.

The study of III-Nitride-based optoelectronics devices is a maturing field with the advent of blue/white LEDs, finding various applications in industry. However, there are still many underdeveloped areas to contribute to new and original research. This work explicitly targets the goals of realizing solar-blind avalanche photodetectors with single photon detection capabilities. Achieving these goals has required systematic optimization of the material growth and characterization, device modeling and design, device fabrication and processing, and device testing. This work describes the research conducted and presents relevant devices results.The AlGaN material system has a tunable direct bandgap that is ideally suited to detection of ultraviolet light; however, this material system suffers from several key issues, making realization of high-efficiency photodetectors complex: large dislocation densities, low n-type and p-type doping efficiency, and lattice and thermal expansion mismatches leading to cracking of the material. These problems are exacerbated by the increased aluminum compositions necessary in back-illuminated and solar-blind devices. Overcoming these obstacles has required extensive development and optimization of the material growth techniques necessary, including everything from the growth of the buffer and template to the growth of the active region.For the first time, the devices realized in this work demonstrate high gain deep UV avalanche photodetectors showing single photon detection capabilities in the solar-blind region. We report gain in excess of 50,000 with a single photon detection efficiency of 5% at 255 nm. This serves as the foundation to realize solar-blind APD arrays with high single photon detection efficiencies. Since dislocation densities arising from the lattice mismatch drive up the dark current and reduce performance of these devices, two approaches were explored to reduce the defect densities in the active AlGaN layers. First, the use of AlN substrates was studied.This work demonstrates low dark current, deep Ultraviolet AlGaN/AlN Photodetectors on AlN substrate. AlGaN based Photodetectors are grown and fabricated both on AlN and Sapphire substrates with the same epilayer structure. Subsequently, electrical characteristics of both photodetectors on AlN substrate and Sapphire are compared. A reduction of 4 orders of magnitude of dark current density is reported in UV detectors grown on AlN substrate with respect to Sapphire substrate. However, no avalanche effects was observed due to impurity related absorptions in the AlN substrate. Therefore, a novel method of epitaxy, namely, Reduced Area Epitaxy (RAE) was employed to demonstrate array based format of avalanche photodetectors in the Deep UV region by reduction of cracks in the active AlGaN layers for detectors grown on Sapphire.This work reports high gain avalanche photodetectors operating in the deep UV wavelength regime. The high gain was leveraged through reduced area epitaxy by patterning AlN on Sapphire substrate. This helps in a substantial reduction of crack formation due to overgrowth on individually isolated AlN mesas. Reproducible gain on the order of 105 was reported for multiple diodes in different areas of 320x256 focal plane array. Therefore, the next step would be to implement these devices in a focal plane array format which will pave the way for commercial realization of back-illuminated avalanche photodetectors in the deep UV region.

ISBN: 9798381976748Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Avalanche photodetectors

Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection.
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245 1 0 $a Solar-Blind Deep UV AlGaN Based Avalanche Photodetectors for Single Photon Detection.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2024
300 $a 161 p.
500 $a Source: Dissertations Abstracts International, Volume: 85-10, Section: B.
500 $a Advisor: Razeghi, Manijeh.
502 $a Thesis (Ph.D.)--Northwestern University, 2024.
520 $a The study of III-Nitride-based optoelectronics devices is a maturing field with the advent of blue/white LEDs, finding various applications in industry. However, there are still many underdeveloped areas to contribute to new and original research. This work explicitly targets the goals of realizing solar-blind avalanche photodetectors with single photon detection capabilities. Achieving these goals has required systematic optimization of the material growth and characterization, device modeling and design, device fabrication and processing, and device testing. This work describes the research conducted and presents relevant devices results.The AlGaN material system has a tunable direct bandgap that is ideally suited to detection of ultraviolet light; however, this material system suffers from several key issues, making realization of high-efficiency photodetectors complex: large dislocation densities, low n-type and p-type doping efficiency, and lattice and thermal expansion mismatches leading to cracking of the material. These problems are exacerbated by the increased aluminum compositions necessary in back-illuminated and solar-blind devices. Overcoming these obstacles has required extensive development and optimization of the material growth techniques necessary, including everything from the growth of the buffer and template to the growth of the active region.For the first time, the devices realized in this work demonstrate high gain deep UV avalanche photodetectors showing single photon detection capabilities in the solar-blind region. We report gain in excess of 50,000 with a single photon detection efficiency of 5% at 255 nm. This serves as the foundation to realize solar-blind APD arrays with high single photon detection efficiencies. Since dislocation densities arising from the lattice mismatch drive up the dark current and reduce performance of these devices, two approaches were explored to reduce the defect densities in the active AlGaN layers. First, the use of AlN substrates was studied.This work demonstrates low dark current, deep Ultraviolet AlGaN/AlN Photodetectors on AlN substrate. AlGaN based Photodetectors are grown and fabricated both on AlN and Sapphire substrates with the same epilayer structure. Subsequently, electrical characteristics of both photodetectors on AlN substrate and Sapphire are compared. A reduction of 4 orders of magnitude of dark current density is reported in UV detectors grown on AlN substrate with respect to Sapphire substrate. However, no avalanche effects was observed due to impurity related absorptions in the AlN substrate. Therefore, a novel method of epitaxy, namely, Reduced Area Epitaxy (RAE) was employed to demonstrate array based format of avalanche photodetectors in the Deep UV region by reduction of cracks in the active AlGaN layers for detectors grown on Sapphire.This work reports high gain avalanche photodetectors operating in the deep UV wavelength regime. The high gain was leveraged through reduced area epitaxy by patterning AlN on Sapphire substrate. This helps in a substantial reduction of crack formation due to overgrowth on individually isolated AlN mesas. Reproducible gain on the order of 105 was reported for multiple diodes in different areas of 320x256 focal plane array. Therefore, the next step would be to implement these devices in a focal plane array format which will pave the way for commercial realization of back-illuminated avalanche photodetectors in the deep UV region.
590 $a School code: 0163.
650 4 $a Electrical engineering. $3 649834
650 4 $a Engineering. $3 586835
650 4 $a Applied physics. $3 3343996
650 4 $a Quantum physics. $3 726746
653 $a Avalanche photodetectors
653 $a Gallium nitride
653 $a Semiconductors
653 $a Single photon detection
653 $a Solid-state physics
690 $a 0544
690 $a 0537
690 $a 0599
690 $a 0215
710 2 $a Northwestern University. $b Electrical and Computer Engineering. $3 1022291
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791 $a Ph.D.
792 $a 2024
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30820281