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Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications = = Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications =/ Huseyin Cakmak.
Reminder of title:	Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi /
Author:	Cakmak, Huseyin,
Description:	1 electronic resource (154 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-04, Section: B.
Contained By:	Dissertations Abstracts International86-04B.
Subject:	Chemical bonds. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31655438
ISBN:	9798342361293

Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications = = Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi /
Cakmak, Huseyin,

Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications =Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi /Huseyin Cakmak. - 1 electronic resource (154 pages)

Source: Dissertations Abstracts International, Volume: 86-04, Section: B.

Gallium Nitride (GaN) based HighElectronMobility Transistor (HEMT) is the most powerful alternative for high-power and high-frequency applications due to its unique material properties, such as high breakdown field, high electron drift velocity, high operation temperatures, high radiation resistance. Low ohmic contact resistance (Rc) is critical to enhancing the device performance at high frequency and high output power. Various metal stacks with different metal types have been reported in literature. Annealing these metal stacks at high temperatures (above 800 °C) leads to a deterioration in the metal surface morphology and metal edge acuity which makes it difficult to carry out further operations to form the gate region. On top of increasing the production costs, high annealing temperatures may also result in thermal degradation of the epitaxial heterostructure.In this work, high temperature annealing of metal stacks was eleminated by the development of MOCVD regrown InGaN layers and ALD grown AZO non-alloyed ohmic contacts, which does not require high temperature annealing of metal pads. These contacts were specifically studied for Ka-band application of GaN-based HEMT devices. To our best knowledge, MOCVD regrown InGaN layers and ALD grown AZO films as non-alloyed ohmic contacts were implemented to GaN-based vi HEMT devices for Ka-band applications first time in literature. MOCVD regrown InGaN layers and ALD grown AZO films exhibited degenerate doping (1019cm-3) low resistivity (~10-3.cm) crucial for ohmic contacts to GaN materials. Improved contacts resistance of non-alloyed regrown InGaN ohmic contacts down to 0.3 .mm compared to HEMT with alloyed ohmic contacts was accomplished. Alloyed ohmic contacts were also optimized with varying the barrier metal, metal thicknesses, and annealing conditions for comparison. 0.41 .mm contact resistance was achieved for the alloyed ohmic contact with Ni barrier and the corresponding HEMT device yielded 2.80 W/mm. An almost 7% improvement was observed in both drain-source current (Ids), transconductance (gm), and small-signal performance. Large-signal measurements showed that the output power of the HEMT with non- alloyed regrown InGaN ohmic contact was 3.07 W/mm which was 9% higher compared to HEMT with alloyed ohmic contacts. Although, initial trials did not yield expected results due to not optimized recess etching and post-plasma cleaning conditions, there is still room for improvement for the ALD of AZO ohmic contacts.

English

ISBN: 9798342361293Subjects--Topical Terms:

560512
Chemical bonds.

Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications = = Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi /
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100 1 $a Cakmak, Huseyin, $e author. $3 3819088
245 1 0 $a Comparison of Alloyed and Non-Alloyed Ohmic Contacts in Gan/Algan Hemt for ka Band Radar Applications = $b Ka Bant Radar Uygulamalari Icin Gan / Algan Hemt Yapilarinda Alasimli Ve Alasimsiz Ohmik Kontaklarin Karsilastirilmasi / $c Huseyin Cakmak.
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300 $a 1 electronic resource (154 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 86-04, Section: B.
500 $a Advisors: Imer, Bilge; Bek, Alpan.
502 $b Ph.D. $c Middle East Technical University (Turkey) $d 2020.
520 $a Gallium Nitride (GaN) based HighElectronMobility Transistor (HEMT) is the most powerful alternative for high-power and high-frequency applications due to its unique material properties, such as high breakdown field, high electron drift velocity, high operation temperatures, high radiation resistance. Low ohmic contact resistance (Rc) is critical to enhancing the device performance at high frequency and high output power. Various metal stacks with different metal types have been reported in literature. Annealing these metal stacks at high temperatures (above 800 °C) leads to a deterioration in the metal surface morphology and metal edge acuity which makes it difficult to carry out further operations to form the gate region. On top of increasing the production costs, high annealing temperatures may also result in thermal degradation of the epitaxial heterostructure.In this work, high temperature annealing of metal stacks was eleminated by the development of MOCVD regrown InGaN layers and ALD grown AZO non-alloyed ohmic contacts, which does not require high temperature annealing of metal pads. These contacts were specifically studied for Ka-band application of GaN-based HEMT devices. To our best knowledge, MOCVD regrown InGaN layers and ALD grown AZO films as non-alloyed ohmic contacts were implemented to GaN-based vi HEMT devices for Ka-band applications first time in literature. MOCVD regrown InGaN layers and ALD grown AZO films exhibited degenerate doping (1019cm-3) low resistivity (~10-3.cm) crucial for ohmic contacts to GaN materials. Improved contacts resistance of non-alloyed regrown InGaN ohmic contacts down to 0.3 .mm compared to HEMT with alloyed ohmic contacts was accomplished. Alloyed ohmic contacts were also optimized with varying the barrier metal, metal thicknesses, and annealing conditions for comparison. 0.41 .mm contact resistance was achieved for the alloyed ohmic contact with Ni barrier and the corresponding HEMT device yielded 2.80 W/mm. An almost 7% improvement was observed in both drain-source current (Ids), transconductance (gm), and small-signal performance. Large-signal measurements showed that the output power of the HEMT with non- alloyed regrown InGaN ohmic contact was 3.07 W/mm which was 9% higher compared to HEMT with alloyed ohmic contacts. Although, initial trials did not yield expected results due to not optimized recess etching and post-plasma cleaning conditions, there is still room for improvement for the ALD of AZO ohmic contacts.
520 $a Galyum Nitrur (GaN) bazli Yuksek Elektron Hareketlilik Transistoru (HEMT), yuksek kirilma alani, yuksek elektron suruklenme hizi, yuksek calisma sicakliklari gibi benzersiz malzeme malzeme ozellikleri nedeniyle yuksek guclu ve yuksek frekansli uygulamalar icin en guclu alternatiftir. Dusuk bir omik temas direnci (Rc), yuksek frekans ve yuksek cikis gucunde cihaz performansini artirmak icin kritik oneme sahiptir.Yuksek sicakliklarda (800 °C'nin uzerinde) metal yiginlarinin tavlanmasi, metal yuzey morfolojisinde ve metal kenar keskinligindebozulmaya yol acar ve bu durum aygit uretiminde basta kapi kontak metal hizalamasi olmak uzere sonraki asamalarin gerceklestirilmesini zorlastirir. Uretim maliyetlerini artirmanin yanisira, yuksek tavlama sicakliklari ayrica epitaksiyel heteroyapikalitesinde bozulmalara neden neden olabilir.Bu calismada, Ka-Band uygulamalari icin, GaN tabanli HEMT aygit uretiminde yuksek sicakliktavlama islemine ihtiyac duymayan MOCVD yeniden buyutme yontemi ile uretilen InGaN tabakalari ve ALD yontemi ile uretilen AZO tabakalari kullanilarak alasimsiz omik kontak gelistirme calismalari yapilmistir.Bu kontaklar ozellikle Ka-Band uygulamalarin icin uretilen GaN tabanli HEMT yapilari icin uygulanmistir.Bildigimiz kadari ile, Ka-bant uygulamalari icin GaN tabanli HEMT aygitlarinda MOCVD yeniden yontemi kullanarak InGaN katmanlarininve ALD yontemi ile uretilen AZO katmanlarimiomik kontak uretimindeuygulayan ilk grup biziz.MOCVD yontemi ile uretilen InGaN tabakalari ve ALD yontemi ile uretilen AZO tabakalari GaN malzemelerine omik kontak yapmak icin oldukca onemli olan yuksek katkilama duzeyi (1019cm-3) ve dusuk tabaka direnci (~10-3.cm) ozelliklerini gosterdiler. Bu calismanin en onemli noktalari arasinda: alasimli omik kontakli HEMT ile karsilastirildiginda, alasimsiz ve MOCVD yontemi ile yeniden buyutulmus InGaN ohmik kontaklarin 0.3 .mm'ye kadar iyilestirilmiskontak direnciyer almaktadir.Karsilastirma amaci ile alasimli omik kontaklar farkli bariyer metali, farkli metal kalinliklari ve farkli tavlama kosullari kullanilarak uretilmislerdir. Ni bariyer metali kullanilarak uretilen HEMT yapilarinda kontak direnci 0.41 .mmcikis gucu ise 2.80 W/mm olarak elde edilmistir. Hem kaynak-akac akimi(Ids), hem transkonduktansta (gm) hem de kucuk sinyal performansinda yaklasik% 7'lik bir iyilesme gozlenmistir. Transistor buyuk sinyal olcumleri, MOCVD yeniden buyutme yontemi ile uretilen InGaN omik kontakli HEMTaygitlarincikis gucunun, alasimli ohmik kontakli HEMTaygitlara kiyasla% 9artarak 3.07 W / mmoldugu gorulmustur.ALD yontemi ile uretilen omik kontaklarda ise ilk denemeler optimize edilmemis girinti asindirma ve plazma sonrasi temizleme kosullari nedeniyle beklenen sonuclari vermedi.
546 $a English
590 $a School code: 2013
650 4 $a Chemical bonds. $3 560512
650 4 $a Electrons. $3 516581
650 4 $a Semiconductors. $3 516162
650 4 $a Zinc oxides. $3 3681737
650 4 $a Atomic physics. $3 3173870
650 4 $a Chemistry. $3 516420
690 $a 0748
690 $a 0485
710 2 $a Middle East Technical University (Turkey). $b Department of Micro and Nanotechnology. $e degree granting institution. $3 3819089
720 1 $a Imer, Bilge $e degree supervisor.
720 1 $a Bek, Alpan $e degree supervisor.
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790 $a 2013
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