{"id":841,"date":"2010-06-28T11:13:24","date_gmt":"2010-06-28T15:13:24","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=841"},"modified":"2010-06-29T14:08:23","modified_gmt":"2010-06-29T18:08:23","slug":"in-situ-deposition-of-high-k-dielectrics-on-a-iii-v-compound-semiconductor-in-an-mocvd-system","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/in-situ-deposition-of-high-k-dielectrics-on-a-iii-v-compound-semiconductor-in-an-mocvd-system\/","title":{"rendered":"In Situ Deposition of High-k Dielectrics on a III-V Compound Semiconductor in an MOCVD System"},"content":{"rendered":"
\"Figure<\/a>

Figure 1: SIMS depth profile of elements C, Ga, and Al. The Ga and Al were plotted in relative intensity (left axis) while the C was plotted in atomic concentration (right axis). The open square symbols represent the fitted error function of the gallium profile. The inserted figure shows TEM image of the CVD oxide\/GaAs structure.<\/p><\/div>\n

We develop an in situ<\/em> manufacturable method to passivate the III-V compound semiconductor (especially the GaAs) in an MOCVD system. The trimethyaluminum (TMA) and isopropanol (IPA) were chosen as the precursors of Atomic Layer Deposition (ALD) of Al2<\/sub>O3 <\/sub>((C.W. Cheng and E.A. Fitzgerald,\u201dIn situ <\/em>metal-organic chemical vapor deposition atomic-layer deposition of aluminum oxide on GaAs using trimethyaluminum and isopropanol precursors,\u201d Applied Physics Letters<\/em>, vol. 93, no. 3, pp. 031902:1-3, July 2008.)). The III-V channel and buffer layer were grown by the CVD mode, and then the passivation Al2<\/sub>O3<\/sub> was deposited by ALD by applying appropriate procedures and growth parameters in the MOCVD system. This design made our CVD machine the first in situ<\/em> passivation CVD machine in the world, and it achieved low interfacial defect density at an oxide\/III-V semiconductor interface. Beside the in situ<\/em> method, the ex situ<\/em> method was investigated to compare the results with the in situ <\/em>method; the self-cleaning effect was also explored in an ex situ <\/em>process by applying TMA\/IPA as ALD precursors [1<\/a>]<\/sup>. Recently, in situ<\/em> deposition of Al2<\/sub>O3<\/sub> on GaAs was performed by Chemical Vapor Deposition (CVD) with the same precursors [2<\/a>]<\/sup>.<\/p>\n

\"Figure<\/a><\/p>\n

Figure 2: C-V characteristics of in situ<\/em> (a) CVD and (b) ALD Al2<\/sub>O3<\/sub> on GaAs. For the inserted figure in (b) Dit<\/sub> distribution of CVD samples in the band-gap extracted by the conductance-frequency method. (c) and (d) <\/em>Gp<\/sub>\/\u03c9-Vg<\/sub>-f map of CVD and ALD samples. The dashed white line represents the position of the peak. The scales of maps (c) and (d) are different.<\/p>\n<\/div>\n

A gallium-rich region in the Al2<\/sub>O3<\/sub> thin film above the interface was observed by using secondary-ion mass spectrometry (SIMS) depth profile measurement (see Figure 1). The X-ray photoelectron spectroscopy (XPS) results show that the gallium-rich region consists of Al2<\/sub>O3<\/sub> and Ga2<\/sub>O3<\/sub>, but no As2<\/sub>O3<\/sub> was observed. The gallium oxide was enriched above the interface during the deposition process. The layer of the Ga2<\/sub>O3<\/sub>– Al2<\/sub>O3<\/sub> above the oxide\/GaAs interface reduces the frequency dispersion of the Capacitance-Voltage (C-V) characteristics and lowers the interfacial defect density (see Figure 2). Both depletion and enhanced-mode MOSFET were fabricated to evaluate the real performance of the device with the in situ<\/em> passivation oxide.<\/p>\n

\r\nReferences
  1. C.W. Cheng, J. Hennessy, D. Antoniadis, and E.A. Fitzgerald, \u201cSelf-cleaning and surface recovery with arsine pretreatment in ex situ <\/em>atomic-layer-deposition of Al2O3 on GaAs,\u201d Applied Physics Letters<\/em>, vol. 95, no. 8, pp. 082106:1-3, Aug. 2009. [↩<\/a>]<\/li>
  2. C.W. Cheng and E.A. Fitzgerald,\u201d<\/em>Improved interfacial state density in Al2<\/sub>O3<\/sub>\/GaAs interfaces using metal-organic chemical vapor deposition,\u201d Applied Physics Letters<\/em>, (Accepted), May 2010. [↩<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"

    We develop an in situ manufacturable method to passivate the III-V compound semiconductor (especially the GaAs) in an MOCVD system….<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[28],"tags":[4075,19],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/841"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=841"}],"version-history":[{"count":6,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/841\/revisions"}],"predecessor-version":[{"id":998,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/841\/revisions\/998"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=841"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=841"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=841"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}