漢字圏学習者の「の」の脱落における言語転移の様相 : 「の」「의」「的」の対応関係に着目して

横浜国立大学Yokohama National University本研究は「の」の脱落による誤用をターゲットとして言語転移の様相を探ろうとするものである。日本語学習者の名詞句における「の」の脱落は,複数の母語を対象とした作文及び発話データから,母語にかかわらず生じる誤用であることが明らかとなっているが,上のレベルになるにつれ漢字圏学習者により多く見られることが指摘されている。そこで本研究では韓国語と中国語を母語とする上級日本語学習者に対して文法性判断テストによる調査を実施し,日本語と同様に修飾部と被修飾部をつなぐ働きをする「의 (韓国語)」「的(中国語)」の有無が,日本語でも母語でも必要な「一致」か,日本語では必要であるが母語では不要な「不一致」か,母語ではあってもなくてもどちらでもよい「任意」かという観点から,「の」の脱落に対する正答率の差を検討した。その結果,中国語母語話者は,「一致」が「不一致」「任意」よりも有意に高く,母語との対応関係が一致しているほど正しく判断していることが明らかとなった。一方,韓国語母語話者は「任意」が「一致」「不一致」よりも有意に高く,母語との対応関係以外の要因が関与している可能性が示された。韓国語では「任意」であるケースが日本語と比較して非常に多く存在することから,韓国語で「任意」の場合には日本語では「の」が必要であるとする,学習者なりの認知的判断が関与している可能性が示された。従来の「正と負の転移」の枠組みでは説明しきれない言語転移のメカニズムの一端として報告する。This study investigated linguistic aspects of language transfer, focusing on the erroneous omission of the Japanese particle no (の). Grammaticality judgments of Japanese examples with no omitted were elicited from advanced-level Japanese learners whose L1 is Korean or Chinese. Three categories were used: (a) MATCHING - The no particle in L2 Japanese and the ui (의) particle in L1 Korean or de (的) particle in L1 Chinese are required. (b) NON-MATCHING - The no is required in L2, but the ui or de is not normally used in L1. (c) OPTIONAL - The L2 particle is required, but the L1 particle is optional. The results show that L1 Chinese learners had a significantly higher rate of correct responses to MATCHING items than to NON-MATCHING or OPTIONAL items, which suggests that learners judge more accurately when the correspondence between L1 and L2 is better. On the other hand, the L1 Korean learners did significantly better on OPTIONAL items than on MATCHING or NON-MATCHING items, which suggests that factors other than the correspondence between L1 and L2 may be involved

GaN, AlGaN, GaNAs and Related Heterostructures Grown by Molecular Beam Epitaxy

This work deals with growth and characterization of III-nitrides and related heterostructures as well as GaNAs alloys grown by plasma assisted molecular beam epitaxy (MBE). The III-nitrides belong to the wide bandgap semiconductors due to their large energy bandgap spanning from 1.9 to 6.2 eV. Owing to their large and direct bandgap, therefore, III-nitrides can be used for violet, blue, and green light emitting diodes (LEDs) as well as for high temperature and high speed-high power transistors. The GaNAs alloys have attracted much attention due to their large and composition-dependent bowing parameter and the corresponding broad span in the bandgap. In addition, this material system can be grown lattice matched to Si, and GaAs when In is incorporated together with N. The subjects of this work consist of three main parts, as described briefly below. Since doping is a critical issue for semiconductor devices, unintentional impurities are also important because they may have detrimental effects on optical and electrical properties. Therefore, we have investigated correlations between growth parameters and residual impurities, especially, B, As and O, incorporated in the GaN layers to identify their possible origins. The B impurity was found to originate from the pBN crucible used in the N plasma source. The relatively high As impurity background level (~3x1018 atoms/cm3) observed in the unintentionally doped GaN is ascribed to the previous growth of arsenides in the same system. By improving the layer crystalline qualities, we could observe a significant reduction of the O impurity levels in the GaN layers. The AlGaN/GaN heterostructure is an important element in electronic devices due to their excellent electrical properties such as electron carrier concentration and mobility, which are ascribed to the existence of a two-dimensional electron gas (2DEG) at the heterointerface. We report about the growth and characterization of the AlxGa1-x N/GaN (x up to 30%) heterostructures. Due to the large miscibility gap in the GaNAs ternary alloy, it was found to be difficult to incorporate high concentration of As in GaN, or N in GaAs. Alternative ways may be to grow thin As-rich layers embedded in GaN, or short period superlattices, (GaN)m(GaAs)n. In this respect, we have studied the growth of a thin As-rich layer buried in wurtzite GaN, and thick GaAs grown on wurtzite GaN. The SIMS analysis demonstrates that an in situ annealing/interruption process at optimized temperature is essential to obtain a well-confined thin As-rich layer embedded in the GaN. A strong evidence of As surface segregation was observed, and analyzed using an one-dimensional empirical segregation model. In addition, the presence of As in wurtzite GaN is found to be responsible for the formation of basal plane stacking faults. The thick GaAs layers grown on GaN (0001) are found to have two preferential growth orientations, i.e., GaAs (111) and (220). The characterization techniques used for this work are summarized as: Secondary Ion Mass Spectrometry (SIMS), High-resolution X-ray Diffraction (HRXRD), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM)

GaN, AlGaN, GaNAs and Related Heterostructures Grown by Molecular Beam Epitaxy

This work deals with growth and characterization of III-nitrides and related heterostructures as well as GaNAs alloys grown by plasma assisted molecular beam epitaxy (MBE). The III-nitrides belong to the wide bandgap semiconductors due to their large energy bandgap spanning from 1.9 to 6.2 eV. Owing to their large and direct bandgap, therefore, III-nitrides can be used for violet, blue, and green light emitting diodes (LEDs) as well as for high temperature and high speed-high power transistors. The GaNAs alloys have attracted much attention due to their large and composition-dependent bowing parameter and the corresponding broad span in the bandgap. In addition, this material system can be grown lattice matched to Si, and GaAs when In is incorporated together with N. The subjects of this work consist of three main parts, as described briefly below. Since doping is a critical issue for semiconductor devices, unintentional impurities are also important because they may have detrimental effects on optical and electrical properties. Therefore, we have investigated correlations between growth parameters and residual impurities, especially, B, As and O, incorporated in the GaN layers to identify their possible origins. The B impurity was found to originate from the pBN crucible used in the N plasma source. The relatively high As impurity background level (~3x1018 atoms/cm3) observed in the unintentionally doped GaN is ascribed to the previous growth of arsenides in the same system. By improving the layer crystalline qualities, we could observe a significant reduction of the O impurity levels in the GaN layers. The AlGaN/GaN heterostructure is an important element in electronic devices due to their excellent electrical properties such as electron carrier concentration and mobility, which are ascribed to the existence of a two-dimensional electron gas (2DEG) at the heterointerface. We report about the growth and characterization of the AlxGa1-x N/GaN (x up to 30%) heterostructures. Due to the large miscibility gap in the GaNAs ternary alloy, it was found to be difficult to incorporate high concentration of As in GaN, or N in GaAs. Alternative ways may be to grow thin As-rich layers embedded in GaN, or short period superlattices, (GaN)m(GaAs)n. In this respect, we have studied the growth of a thin As-rich layer buried in wurtzite GaN, and thick GaAs grown on wurtzite GaN. The SIMS analysis demonstrates that an in situ annealing/interruption process at optimized temperature is essential to obtain a well-confined thin As-rich layer embedded in the GaN. A strong evidence of As surface segregation was observed, and analyzed using an one-dimensional empirical segregation model. In addition, the presence of As in wurtzite GaN is found to be responsible for the formation of basal plane stacking faults. The thick GaAs layers grown on GaN (0001) are found to have two preferential growth orientations, i.e., GaAs (111) and (220). The characterization techniques used for this work are summarized as: Secondary Ion Mass Spectrometry (SIMS), High-resolution X-ray Diffraction (HRXRD), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM)