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Al/p-Ge(100)接合界面に意図的に極薄熱酸化GeO_2を形成し、N_2熱処理によるショットキー障壁高さおよび化学構造の変化の相関を電流-電圧(I-V)特性および硬X線光電子分光法(HAXPES)より評価した。300℃以上のN_2熱処理によりAl/GeO_2界面でGeO_2の還元が促進し、Ge価電子帯上端に金属の実効的な仕事関数が固定されるフェルミレベルピニング(FLP)現象が顕在化する。GeO_2の代わりに、N_2雰囲気中スパッタ法で極薄HfN層を導入すると、450℃の熱処理に対してもFLP緩和に有効であった。極薄膜を用いた伝導特性制御において、熱的に安定な接合界面の形成には、効果的にN導入することが重要である。, The impact of thermal annealing in N_2 ambience on schottky barrier height (SBH) and chemical structures of Al/p-Ge(100) junctions with an interfacial control layer such as GeO_2 and HfN have been investigated from the current density-voltage (I-V) characteristics and hard X-ray photoemission spectroscopy (HAXPES), respectively. We found that, by N_2 annealing at temperatures over 300℃, the GeO_2 reduction in the region near the Al/GeO_2 interface is promoted and the Fermi level pinning (FLP) effect is induced significantly. Such a reduction of SBH in Al/p-Ge(100) junction with annealing was suppressed by an insertion of ultrathin HfN layer instead of GeO_2. The introduction of N atoms in the region near the Al/p-Ge(100) interface is likely to be effective to suppress the reveal of FLP effect with annealing.

GeチャネルMISFET実現のために必要不可欠なHigh-k/Ge界面制御手法として、極薄TaOx層の挿入に着目し、Ge表面へのTaO_xのMOCVDによるLayer-by-Layer成膜を行い、界面近傍の化学結合状態について評価を行った。その結果、HfO_2/Ge界面に形成したTaO_x挿入層/Ge界面近傍で成膜中および成膜後の熱負荷によるTaO_x層中へのGeの拡散が確認されるものの、厚さ〜1nm以上のTaO_x挿入が、誘電率低下の要因となるGe界面酸化層の形成抑制に有効であることが明らかとなった。また、Ge拡散により界面に形成されたTaGe_xO_y層の比誘電率は、GeO_2の値の約1.7倍の9であることから、EOT低減に効果的であることを明らかにした。, To control interfacial reaction between high-k dielectric and Ge, we have focused on an insertion of TaO_x ultrathin layer as an interfacial barrier layer and studied MOCVD process of TaO_x with layer-by-layer fashion on Ge surface. XPS analyses show that Ge atoms diffuses into TaO_x layer during the formation of HfO_2 and cofirm that the Ge-oxide growth during atomic layer deposition of HfO_2 is effectively suppressed by inserting TaO_x layer thicker than 1nm. The dielectric constant of TaGe_xO_y layer formed by Ge atoms diffusion into TaO_x layer was determined to be 〜9 being larger by a factor of 1.7 than that of GeO_2 (ε〜5.2).

資料番号: AA0048709001, レポート番号: JAXA-RR-04-044E

Dynamic structures of liquid germanium at the temperature of 1,253 K were investigated by a first-principles molecular-dynamics simulation. To investigate long-range correlation functions the MD simulation was carried out not only with a cubic cell but also with a rectangular parallelepiped cell. The calculated dynamic structure factors and the dispersion relation are in excellent agreement with the results of a recent inelastic X-ray scattering experiment., 資料番号: AA0045399006, レポート番号: NASDA-TMR-020025E

Density measurement by the high-energy gamma ray attenuation method was briefly summarized. The results obtained for molten Ge and Sn up to 1,200 C were presented in comparing with those measured with other techniques., 資料番号: AA0045399010, レポート番号: NASDA-TMR-020025E

The dynamical structure factors of the liquid Ge are calculated theoretically and compared with the recent experimental results obtained by the inelastic x-ray scattering. The calculation is carried out by the simple purely theoretical method, i.e. by the viscoelastic theory, which is based on the effective pair potential obtained by the pseudopotential perturbation theory and the static structure factor calculated by the integral-equation theory in the modified hypernetted-chain (MHNC) approximation. It is shown that the calculated dynamical structure factors are in qualitative agreement with the experimental results and that the calculated dispersion relation agrees well with the experimental one., 資料番号: AA0045399001, レポート番号: NASDA-TMR-020025E

To establish the shear cell technique for the diffusion coefficient measurement of high vapor pressure sample, the seal effect of B2O3 melts was investigated by using a simplified shear cell unit. Moreover, the seal effect was investigated by using a short form shear cell. Even for liquid samples with high vapor pressures, the seal effect of B2O3 can be expected., 資料番号: AA0045399013, レポート番号: NASDA-TMR-020025E

高純度かつ高品位の材料を得るためには、材料加工にとって試料と容器の濡れ性は、特に微小重力(マイクロG)環境下では、重要な因子である。SiO2容器への濡れ性に及ぼすSn、Ge、およびGaSb試料の精製処理による効果を1GおよびマイクロG環境下で検討した。処理は真空加熱、水素ガス中加熱および塩素ガス雰囲気中での加熱溶融を行った。試料と容器の濡れ挙動は精製処理の各種類ごとに変化した。(1)塩素ガス雰囲気中での加熱溶融は、Sn試料に対してSiO2容器への濡れ性を改善するのに効果があった。(2)Sn試料については、試料と容器の濡れ性は表面酸化物層の厚さと関連がある。(3)水素ガス雰囲気中での加熱はGeおよびGaSb試料に対する濡れ性を改善するのに効果があった。, A sample/container wettability is an important factor for material processing, especially in microgravity (micro-g) environment, to get high purity and high quality materials. The effect of refining treatment of Sn, Ge and GaSb samples on wettability to SiO2 container was investigated both in 1-g and micro-g environment. The treatments were heating in vacuum, heating in H2 gas and heating/melting in Cl2 gas atmosphere. The sample/container wetting behavior was changed for each kind of refining treatments. (1) The heating/melting in Cl2 gas atmosphere was effective to improve the wettability to SiO2 container for Sn sample. (2) The sample/container wettability was related to the thickness of the surface oxide layers for Sn sample. (3) The heating in H2 gas atmosphere was effective to improve the wettability for Ge and GaSb samples., 資料番号: AA0000741005, レポート番号: NASDA-TMR-960024

高純度・高品質の材料処理において、材料と容器の濡れ性は、とくに微小重力(マイクロg)環境下では重要な因子である。Sn、Bi、Geの精製処理の、SiO2容器に対する濡れ性への効果について、1gおよびマイクロgの両環境下で実験調査を行った。酸(HCl)による原材料の前処理をして、真空下、H2およびCl2雰囲気中で処理を行った。精製処理の違いによる材料と容器の濡れ挙動に次のような差異が観察された。(1)SnおよびBiにおける材料と容器の濡れ挙動は表面酸化層の厚みに関係がある。(2)原材料の前処理は濡れ性改善に効果がある。(3)GeのCl2雰囲気中での濡れ挙動は温度(1,280-1,370K)の影響が、特にマイクロg環境下で大きい。宇宙実験に向けて、航空機実験による、材料と容器の各組み合わせにおける濡れ性改善のための最適精製処理条件のスクリーニングは重要である。, A sample/container wettability is an important factor for material processing, especially in microgravity (micro g) environment, to get high purity and high quality materials. The effect of refining treatment of Sn, Bi and Ge samples on wettability to SiO2 container was investigated both in 1 g and micro g environment. The treatments were conducted in vacuum, in H2 gas, and in Cl2 gas atmosphere including pretreatment of raw materials by acid (HCl). The sample/container wetting behavior was changed for each kind of refining treatments: (1) the sample/container wettability was related to the thickness of the surface oxide layers for Sn and Bi samples; (2) the pretreatment of raw materials was effective to improve the wettability; and (3) the wetting behavior of Ge sample in Cl2 gas atmosphere was depended on the temperature (1,280-1,370 K) especially in a micro g environment. For the experiments in space, it is important to screen the most suitable refining treatment for improvement of wettability for each combination of sample and container by aircraft experiments., 資料番号: AA0000738002, レポート番号: NASDA-TMR-960021

資料番号: AA0048709000, レポート番号: JAXA-RR-04-044E

資料番号: AA0045399000, レポート番号: NASDA-TMR-020025E