{"title":"150 nm copper metalized GaAs pHEMT with Cu/Ge ohmic contacts","authors":"E. Anichenko, V. Arykov, E. Erofeev, V. Kagadei","doi":"10.1155/2012/418264","DOIUrl":"https://doi.org/10.1155/2012/418264","url":null,"abstract":"The fully Cu-metalized GaAs pHEMT using developed Cu/Ge based ohmic contacts and Ti/Mo/Cu 150 nm T-shape gate has been successfully fabricated for the high-frequency applications. The fabricated Cu-metalized pHEMT has a maximum drain current of 360 mA/mm, off-state gate-drain breakdown of 7 V and a transconductance peak of 320 mS/mm at VDS = 3V. The maximum stable gain value was about 15 dB at frequency 10 GHz. The current gain cut-off frequency of the copper metalized device is about 60 GHz at Vds = 3 V and maximum frequency of oscillations is beyond 100 GHz. The work investigated in detail the formation of Cu/Ge ohmic contacts to n-GaAs with an atomic hydrogen pre-annealing step. It was shown that when the first preliminary annealing is carried out in a flow of atomic hydrogen with a flow density of atoms of 1013–1016 at. cm2 s−1 a reduction in specific contact resistance by 2–2.5 times is observed. The reduction in specific contact resistance is apparently caused by the action of the hydrogen atoms which minimise the rate of the oxidizing reactions and activate solid phase reactions forming the ohmic contact during the thermal treatment process.","PeriodicalId":227958,"journal":{"name":"The 5th European Microwave Integrated Circuits Conference","volume":"764 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116411163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Erofeev, S. Ishutkin, V. Kagadei, K. S. Nosaeva
{"title":"Multilayer low-resistance Ge/Au/Ni/Ti/Au based ohmic contact to n-GaAs","authors":"E. Erofeev, S. Ishutkin, V. Kagadei, K. S. Nosaeva","doi":"10.1117/12.853581","DOIUrl":"https://doi.org/10.1117/12.853581","url":null,"abstract":"The work investigates the influence of the mode and conditions for deposition of a Ti thin film on the specific contact resistance and thermal stability of Ge/Au/Ni/Ti/Au based ohmic contacts to n-GaAs. Deposition techniques of a Ti diffusion barrier were developed in which a fifty-fold reduction in specific contact resistance was observed, and also an increase in the thermal stability of the sidewalls morphology on the edge of the contact pads. The factors influencing the specific contact resistance are: the angle at which the titanium atoms impact on the GaAs surface, the rate of deposition of the Ti film, and also the residual pressure during deposition. The factor which has an influence on the thermal stability of the sidewalls morphology of the contact pads appears to be the angle of incidence of the Ti atoms.","PeriodicalId":227958,"journal":{"name":"The 5th European Microwave Integrated Circuits Conference","volume":"34 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116593213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}