Papers by Keyword: p-Type

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Authors: Howard E. Smith, Bang Hung Tsao, James D. Scofield
Abstract: The accuracy of Secondary Ion Mass Spectrometry (SIMS) depth profiles of aluminum (Al) dopant in silicon carbide (SiC) has been investigated. The Al SIMS profile differs in shape depending on whether it was obtained using a cesium (Cs+) or oxygen (O2 +) primary ion beam, and depends in the former case on which secondary ion is followed. The matrix signals indicate that the CsAl+ secondary ion yield changes during the Cs+ depth profile, probably because of the work function lowering due to the previously-implanted Al. These same matrix ion signals are used for a depth-dependent empirical correction to increase the accuracy of the Al concentration profile. The physics of these phenomena and the accuracy of the correction are discussed.
Authors: Takeshi Mitani, Shinichi Nakashima, Masaru Tomobe, Shi Yang Ji, Kazutoshi Kojima, Hajime Okumura
Abstract: We have investigated Raman spectra of p-type 4H-SiC crystals with hole concentration ranging from 3×1016 to 1×1021 cm-3. For folded transverse acoustic (FTA) doublet modes, Fano interference profiles were analyzed, and the frequency shift due to Fano interference was obtained as a function of hole concentration. We demonstrated that the shift of the FTA doublet modes is a quantitative measure for evaluating of hole concentration of p-type 4H-SiC. Spectral features of transverse optical (TO) and longitudinal optical phonon-plasmon coupled (LOPC) modes were also studied for various carrier concentrations. The results show that the full width at half maximum of the LOPC and relative intensity of TO and the LOPC can be used as other calibration measures for hole concentration.
Authors: Kazutoshi Kojima, Masahito Yoshikawa, Takeshi Ohshima, Hisayoshi Itoh, Sohei Okada
Authors: Shi Yang Ji, Ryoji Kosugi, Kazutoshi Kojima, Kazuhiro Mochizuki, Yasuyuki Kawada, Kohei Adachi, Shingo Saito, Akiyo Nagata, Yasuko Matsukawa, Yoshiyuki Yonezawa, Sadafumi Yoshida, Hajime Okumura
Abstract: By mapping the source and HCl flow rates dependent growth rates, the evolving trend of a quasi-selective epitaxial growth (quasi-SEG) that growing very thin epilayer on mesa top and ensuring an extremely low risk of voids defect generation was firstly figured out on a 5-μm 4H-SiC trench. Then, basing on the acquired knowledge, a 25-μm 4H-SiC trench with an aspect ratio up to ~10 was completely filled in the quasi-SEG mode.
Authors: L. Storasta, Isaho Kamata, Tomonori Nakamura, Hidekazu Tsuchida
Abstract: We have investigated the electrically active deep level defects in p- and n-type 4H-SiC after low energy electron irradiation. Intrinsic defects were created by irradiation with 200 keV electrons, with energy sufficient to move only the carbon atoms in SiC lattice. Defect spectra were compared between the p- and n-doped samples prepared under identical irradiation conditions. We probed both conduction and valence band sides of the band-gap by using capacitance transient techniques with electrical and optical trap filling. We have found that the defect spectrum in the p-type epilayers differs significantly from the n-type. The Z1/Z2, EH1 and EH3 electron traps which are usually present in irradiated n-type material could not be detected in p-type samples. An electron trap at 1.6 eV below the conduction band edge is present in both n- and p-type samples at the same energy position and with similar concentration, therefore it is probably related to the same type of defect. We have also found a new hole trap in p-type epilayers at energy EV + 0.66 eV.
Authors: Evgeny Yurievich Gusev, Oleg Alekseevich Ageev, Vladislav Anatolyevich Gamaleev, Aleksander Sergeevich Mikhno, Olga Olegovna Mironenko, Evgeniy Anatol'evich Pronin
Abstract: Nanocrystalline ZnO films were deposited by rf reactive magnetron sputtering. The films were characterized by reflection high-energy electron diffraction, X-ray photoelectron spectroscopy and gas sensing measurements. It was found that annealing of the film enabled to invert its conductivity type. Thus, as-deposited ZnO film showed p-type conductivity while annealed film showed n-type conductivity behavior. The p-and n-type conductivities of the films obtained by gas sensing measurements have been confirmed by XPS results. The gas sensing properties of the films were investigated upon exposure to 10 ppm of NO2 at 22°C and exhibited good sensitivity with fast response and recovery times. The sensor response to NO2 was found to be profoundly dependent on the conductivity behavior of the film.
Authors: Li Dan Tang, Bing Wang, Jian Zhong Wang
Abstract: Transparent ZnO:Al films deposited by RF/DC magnetron sputtering in room temperature are annealed under gaseous ammonia ambient and air ambient, respectively. The characteristics of ZnO films are examined by XRD, SEM, Hall measurement and optical transmission spectra. The XRD and SEM analysis shows that both films are crystallized in the wurzite phase with a preferential orientation along the c-axis and have a smooth dense surface. Hall measurement results indicate ZnO:Al films annealed under ammonia ambient convert to p-type conduction with the high carrier concentration of 8.3×1018 cm-3. Optical transmission spectra show a high transmittance (~85%) in the visible region.
Authors: Jun Feng Chen
Abstract: Although the research of bulk GaN material has take great progress in recent years, while the high quality of p-type GaN material still is an obstacle to fabricate the HBT and LD devices. In this paper we growth a group of Mg doped AlGaN/GaN superlattices under variant conditions. The Hall, AFM, PL and HR-XRD measurement are taken to find the relationship of sample quality with the superlattice structure, growth and annealing conditions. The results show that the period length of about 9nm and Al content of 30% is the optimal structure; the best annealing temperature under tmosphere is about 540°C to 580°C. At last the p-type AlGaN/GaN superlattice with resistivity of 0.31Ω•cm is fabricated which can be utilize for the contact layers of blue LEDs.
Authors: Norbert Schulze, Jürgen Gajowski, Kurt Semmelroth, Michael Laube, Gerhard Pensl
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