[ { "id": "authors:5esjw-sc930", "collection": "authors", "collection_id": "5esjw-sc930", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:STRIjap03", "type": "article", "title": "Piezoelectrically enhanced capacitive strain sensors using GaN metal-insulator-semiconductor diodes", "author": [ { "family_name": "Strittmatter", "given_name": "R. P.", "clpid": "Strittmatter-R-P" }, { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "Picus", "given_name": "G. S.", "clpid": "Picus-G-S" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "We report on the use of metal-insulator-semiconductor (MIS) diodes, formed on n-GaN with SiO2, for capacitive strain sensing. These diodes, when subjected to static strain, were found to exhibit a steady-state change in capacitance. As a result, they can be used to detect strain with frequencies all the way down to dc. We formulate a model to explain the action of piezoelectricity in the diode and obtain excellent agreement with measurements. The model is then used to develop design criteria which optimize the sensitivity of the diode to detect strain. The sensitivity of the devices tested here rivals that of the best silicon piezoresistive sensors, but could attain nearly tenfold improvement with only minor design changes. Finally, we consider the effects of interface states on sensor performance and demonstrate how static strain sensing in GaN MIS diodes is enabled by the high quality of the oxide interface.", "doi": "10.1063/1.1611267", "issn": "0021-8979", "publisher": "Journal of Applied Physics", "publication": "Journal of Applied Physics", "publication_date": "2003-11-01", "series_number": "9", "volume": "94", "issue": "9", "pages": "5958-5963" }, { "id": "authors:be9gt-r7632", "collection": "authors", "collection_id": "be9gt-r7632", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:PREjvstb01", "type": "article", "title": "Stability of cerium oxide on silicon studied by x-ray photoelectron spectroscopy", "author": [ { "family_name": "Preisler", "given_name": "E. J.", "clpid": "Preisler-E-J" }, { "family_name": "Marsh", "given_name": "O. J.", "clpid": "Marsh-O-J" }, { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "The silicon-cerium oxide interface is studied using x-ray photoelectron spectroscopy. The oxidation and reduction of species at the interface are examined as a function of annealing temperature both in vacuum and oxygen ambient, in order to determine their relative stabilities. By depositing a very thin CeO2 film (similar to 30 Angstrom), the cerium and silicon core level peaks can be monitored simultaneously. The presence of characteristic chemical shifts of the Si 2p peak gives information about any SiOx, layer that may form at the interface. The oxidation state of the cerium can be probed from three different areas of the spectrum. From this information we can infer the oxidation state of both the silicon and the cerium. For the first time a complete picture of the interface is obtained. The implications of these findings on the utility of CeO2 in device applications are discussed.", "doi": "10.1116/1.1387464", "issn": "1071-1023", "publisher": "American Vacuum Society", "publication": "Journal of Vacuum Science and Technology B", "publication_date": "2001-07", "series_number": "4", "volume": "19", "issue": "4", "pages": "1611-1618" }, { "id": "authors:s2a29-2tb31", "collection": "authors", "collection_id": "s2a29-2tb31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111130-095036875", "type": "article", "title": "Nickel layers on indium arsenide", "author": [ { "family_name": "Hill", "given_name": "C. J.", "clpid": "Hill-C-J" }, { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "We report here on the preparation and characterization of InAs substrates for in situ deposition of ferromagnetic contacts, a necessary precursor for semiconductor devices based on spin injection. InAs has been grown on InAs(111)A and (100) substrates by molecular-beam epitaxy and then metalized in situ in order to better understand the mechanisms that inhibit spin injection into a semiconductor. Initial x-ray characterization of the samples indicate the presence of nickel arsenides and indium\u2013nickel compounds forming during deposition at temperatures above room temperature. Several temperature ranges have been investigated in order to determine the effect on nickel-arsenide formation. The presence of such compounds at the interface could greatly reduce the spin-injection efficiency and help elucidate previous unsuccessful attempts at measuring spin injection into InAs.", "doi": "10.1116/1.1306283", "issn": "1071-1023", "publisher": "American Vacuum Society", "publication": "Journal of Vacuum Science and Technology B", "publication_date": "2000-07", "series_number": "4", "volume": "18", "issue": "4", "pages": "2044-2046" }, { "id": "authors:reask-x0m38", "collection": "authors", "collection_id": "reask-x0m38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BEAjvstb99", "type": "article", "title": "Piezoelectric fields in nitride devices", "author": [ { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "We have calculated the piezoelectric field and charge distribution for various III-nitride heterostructures. Our calculations include strain energy minimization and doping effects, and are presented to show the magnitude of piezoelectric effects in strained layers. We compare our calculated results to device results where available. These include the two-dimensional electron gas in heterojunction field effect transistors, Schottky diodes with strained layers for Schottky height engineering, and III-nitride single quantum wells. Calculations that included energy considerations resulted in good agreement between predicted and observed field and charge distributions for the heterojunction fields-effect transistors structure.", "doi": "10.1116/1.590820", "issn": "1071-1023", "publisher": "American Vacuum Society", "publication": "Journal of Vacuum Science and Technology B", "publication_date": "1999-07", "series_number": "4", "volume": "17", "issue": "4", "pages": "1753-1756" }, { "id": "authors:143c6-q6118", "collection": "authors", "collection_id": "143c6-q6118", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BEAmrsijnsr99", "type": "article", "title": "XPS Study of Oxygen Adsorption on (3x3) Reconstructed MBE Grown GaN Surfaces", "author": [ { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "Piquette", "given_name": "E. C.", "clpid": "Piquette-E-C" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "The incorporation of oxygen onto the (3x3) reconstructed surface of GaN(0001) has been studied using X-ray Photoelectron Spectroscopy (XPS). It was found that the (3x3) reconstruction corresponds to a fractional Ga adlayer atop a Ga terminated GaN surface. Our measurements indicate a surface coverage of 1.15 \u00b1 0.2 monolayers of relaxed Ga on the surface. The binding energy separation between the relaxed surface Ga3d core level and bulk Ga3d level was measured to be 1.1 \u00b1 0.1 eV. A metallic component extending from the bulk GaN valence band maximum out to 0 eV was also present in the XPS spectrum. The separation between the bulk valence band maximum and the Fermi level of the metallic component was found to be 2.1 \u00b1 0.1 eV. The relaxation of the surface Ga was found to decrease with oxygen exposure indicating Ga-O bonding, with oxygen adsorption terminating at 1.3 \u00b1 0.2 monolayers. The O1s core level was found to have a FWHM of 2.0 \u00b1 0.1 eV.", "issn": "1092-5783", "publisher": "MRS Internet Journal of Nitride Semiconductor Research", "publication": "MRS Internet Journal of Nitride Semiconductor Research", "publication_date": "1999", "series_number": "S1", "volume": "4", "issue": "S1", "pages": "Art. No. G6.26" }, { "id": "authors:yyy70-f6889", "collection": "authors", "collection_id": "yyy70-f6889", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:PIQmrsijsnr99", "type": "article", "title": "Effect of Buffer Layer and III/V Ratio on the Surface Morphology of GaN Grown by MBE", "author": [ { "family_name": "Piquette", "given_name": "E. C.", "clpid": "Piquette-E-C" }, { "family_name": "Bridger", "given_name": "P. M.", "clpid": "Bridger-P-M" }, { "family_name": "Beach", "given_name": "R. A.", "clpid": "Beach-R-A" }, { "family_name": "McGill", "given_name": "T. C.", "clpid": "McGill-T-C" } ], "abstract": "The surface morphology of GaN is observed by atomic force microscopy for growth on GaN and AlN buffer layers and as a function of III/V flux ratio. Films are grown on sapphire substrates by molecular beam epitaxy using a radio frequency nitrogen plasma source. Growth using GaN buffer layers leads to N-polar films, with surfaces strongly dependent on the flux conditions used. Flat surfaces can be obtained by growing as Ga-rich as possible, although Ga droplets tend to form. Ga-polar films can be grown on AlN buffer layers, with the surface morphology determined by the conditions of buffer layer deposition as well as the III/V ratio for growth of the GaN layer. Near-stoichiometric buffer layer growth conditions appear to support the flattest surfaces in this case. Three defect types are typically observed in GaN films on AlN buffers, including large and small pits and \"loop\" defects. It is possible to produce surfaces free from large pit defects by growing thicker films under more Ga-rich conditions. In such cases the surface roughness can be reduced to less than 1 nm RMS.", "issn": "1092-5783", "publisher": "MRS Internet Journal of Nitride Semiconductor Research", "publication": "MRS Internet Journal of Nitride Semiconductor Research", "publication_date": "1999", "volume": "4S1", "pages": "Art. No. G3.77" } ]