@article{ojha_kasanaboina_reynolds_rawdanowicz_liu_white_iyer_2016, title={Incorporation of Be dopant in GaAs core and core-shell nanowires by molecular beam epitaxy}, volume={34}, ISSN={["2166-2746"]}, DOI={10.1116/1.4943600}, abstractNote={Effective implementation of doped nanowires (NWs) in nanoscaled devices requires controlled and effective dopant incorporation. The one dimensional configuration of NWs poses a challenge for efficient doping due to the large number of surface states pinning the Fermi level close to the middle of the band gap and thus creating a large depletion layer at the surface. This effectively reduces the effective volume for doping. However, the flexibility of different architectures offered by the NWs, in particular, the core–shell configuration along with different growth mechanisms associated with the core and shell can be strategically used for efficient doping. In this work, the authors report on a catalyst free Ga-assisted approach for the growth of Be-doped GaAs NWs by molecular beam epitaxy. A systematic and a comprehensive study is reported using a variety of characterization techniques to determine the impact of NW configuration, Be cell temperature, and V/III beam equivalent pressure (BEP) ratio individually on doping incorporation in the NWs. Broadening of the photoluminescence spectra in the 1.49–1.51 eV range, as well as the longitudinal optical mode of the corresponding Raman spectra in combination with its red shift that is considered as a signature of higher Be incorporation, was found to occur for the core–shell configuration. Further, a lower V/III BEP ratio has a strong impact on enhancing the dopant incorporation.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Ojha, Sai Krishna and Kasanaboina, Pavan Kumar and Reynolds, Claude Lewis, Jr. and Rawdanowicz, Thomas A. and Liu, Yang and White, Ryan M. and Iyer, Shanthi}, year={2016}, month={Mar} }
 @article{seifikar_rawdanowicz_straka_quintero_bassiri-gharb_schwartz_2014, title={Structural and magnetic properties of sol-gel derived NiFe2O4 thin films on silicon substrates}, volume={361}, ISSN={["1873-4766"]}, DOI={10.1016/j.jmmm.2014.03.004}, abstractNote={Spinel NiFe2O4 thin films are derived via chemical solution deposition on silicon substrates. The films show a granular microstructure with surface roughness of less than 3 nm. The effects of varying the pyrolysis and annealing conditions on the microstructure and resulting magnetic properties have been studied. Microstructural studies confirm the formation of randomly oriented, phase-pure spinel nickel ferrite for pyrolysis at 100 °C to 500 °C and crystallization at 650 °C to 900 °C for 10 to 30 min. It is shown that the pyrolysis temperature does not affect the microstructure and the resulting magnetic properties, while increasing annealing temperature results in increased grain size and saturation magnetization. Transmission electron microcopy shows that no intermediate or secondary phase has formed at the interface even at annealing temperature as high as 900 °C.}, journal={JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS}, author={Seifikar, Safoura and Rawdanowicz, Thomas and Straka, Weston and Quintero, Christopher and Bassiri-Gharb, Nazanin and Schwartz, Justin}, year={2014}, month={Jun}, pages={255–261} }
 @article{seifikar_tabei_sachet_rawdanowicz_bassiri-gharb_schwartz_2012, title={Growth of (111) oriented NiFe2O4 polycrystalline thin films on Pt(111) via sol-gel processing}, volume={112}, ISSN={["1089-7550"]}, DOI={10.1063/1.4752725}, abstractNote={Polycrystalline NiFe2O4 (NFO) thin films are grown on (111) platinized Si substrates via chemical solution processing. θ-2θ x-ray diffraction, x-ray pole figures and electron diffraction indicate that the NFO has a high degree of 〈111〉 uniaxial texture normal to the film plane. The texturing is initiated by nucleation of (111) planes at the Pt interface and is enhanced with decreasing film thickness. As the NFO magnetic easy-axis is 〈111〉, the out-of-plane magnetization exhibits improved Mr/Ms and coercivity with respect to randomly oriented films on silicon substrates. The out-of-plane Mr/Ms ratio for (111) textured NFO thin film is improved from 30% in 150 nm-thick films to above 70% in 50 nm-thick films. The improved out-of-plane magnetic anisotropy is comparable to epitaxial NFO films of comparable thickness deposited by pulsed laser deposition and sputtering.}, number={6}, journal={JOURNAL OF APPLIED PHYSICS}, author={Seifikar, Safoura and Tabei, Ali and Sachet, Edward and Rawdanowicz, Thomas and Bassiri-Gharb, Nazanin and Schwartz, Justin}, year={2012}, month={Sep} }
 @article{bharatan_iyer_li_rawdanowicz_reynolds_2011, title={Study of molecular beam epitaxially grown InGaAsSbN/GaSb single quantum wells}, volume={29}, ISSN={["2166-2746"]}, DOI={10.1116/1.3555368}, abstractNote={InGaAsSbN quantum wells (QWs) have been investigated for potential light-emitting devices in the midinfrared region. This paper presents the growth and properties of molecular beam epitaxially grown InGaAsSbN single QWs using a variety of characterization techniques. A 10 K photoluminescence emission at 2.27 μm, with a lowest full width at half maxima of 5 meV which shifted to 2.30 μm on in situ annealing, has been observed. The presence of well resolved Pendellosung fringes in high resolution x-ray diffraction and sharp abrupt interfaces in the corresponding transmission electron microscope (TEM) images are indications of the high quality of these QWs. Raman spectroscopy studies reveal the presence of well resolved Raman peaks with higher intensity, along with the presence of sharp second order modes of GaSb, further attesting to the high quality of the QW structures grown. Investigation of the annealed samples using Z-contrast scanning TEM images reveals atomic interdiffusion between the QW and surrounding GaSb layers, increasing the effective thickness of the QW, which explains the redshift upon annealing.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Bharatan, Sudhakar and Iyer, Shanthi and Li, Jia and Rawdanowicz, Thomas A. and Reynolds, Lewis, Jr.}, year={2011}, month={May} }
 @article{rawdanowicz_narayan_2004, title={Epitaxial GaN on Si(111): Process control of SiNx interlayer formation}, volume={85}, ISSN={["1077-3118"]}, DOI={10.1063/1.1771803}, abstractNote={The heteroepitaxial growth of (0001) GaN thin films directly on (111) Si by laser-molecular beam epitaxy without the formation of a SiNx interlayer at the GaN∕Si interface is reported. We also find that SiNx can be formed subsequently as a result of nitrogen diffusion to the GaN∕Si(111) interface. The orientation relationship of GaN on Si(111) was determined using x-ray diffraction and selected area electron diffraction. The atomic structure of the interfaces was studied by high resolution transmission electron microscopy. A Fourier filtered image of the cross-sectional GaN∕Si(111) interface demonstrated domain matching epitaxy of 6:5. Distributions of N and Ga concentrations near the GaN∕Si interface were determined using electron energy loss spectroscopy.}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={Rawdanowicz, TA and Narayan, J}, year={2004}, month={Jul}, pages={133–135} }
 @article{rawdanowicz_iyer_mitchel_saxler_elhamri_2002, title={Electronic properties of heteroepitaxial undoped and n-InSb epilayers using SnTe source by molecular beam epitaxy}, volume={92}, ISSN={["0021-8979"]}, DOI={10.1063/1.1476086}, abstractNote={We report on the electrical characteristics of InSb and n-type doping of InSb layers grown on GaAs substrates using a SnTe captive source by molecular beam epitaxy (MBE). The undoped epilayers are n-type in the temperature range of 10 to 300 K investigated. Doped layer with carrier concentrations ranging from 2×1016/cm3 to 3.2×1018/cm3 with corresponding x-ray full width at half maxima varying from 170–200 arcsec have been achieved. High carrier mobility of 94 098 cm2/V s on lightly doped samples has been achieved. These results suggest SnTe source as being one of the donor dopants of choice for MBE grown InSb epilayers. Temperature and magnetic field dependent Hall and resistivity measurements with various multicarrier conduction analysis techniques indicate three conduction channels for undoped InSb and two conduction channels for doped InSb. They have been used successfully to explain the temperature and thickness dependence of the electrical properties of MBE grown undoped and doped InSb epilayers.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Rawdanowicz, TA and Iyer, S and Mitchel, WC and Saxler, A and Elhamri, S}, year={2002}, month={Jul}, pages={296–301} }