952 resultados para city hall


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We report on high magnetic fields (up to 40 T) cyclotron resonance, quantum Hall effect and Shubnikov-de-Hass measurements in high frequency transistors based on Si-doped GaN-AlGaN heterojunctions. A simple way of precise modelling of the cyclotron absorption in these heterojunctions is presented, We clearly establish two-dimensional electrons to be the dominant conducting carriers and determine precisely their in-plane effective mass to be 0.230 +/- 0.005 of the free electron effective mass. The increase of the effective mass with an increase of two-dimensional carrier density is observed and explained by the nonparabolicity effect. (C) 1997 American Institute of Physics.

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讨论了外延及注入制作的薄层GaAs Hall器件如何获得高的磁线性度。GaAs Hall器件的磁线性度在高磁场下会有偏离,但可以通过外延及注入的过渡层对有源区进行补偿,在合适的有源区和过渡区的浓度和厚度分布中,可以得到在2.5T的强磁场下,±0.04%的高磁线性度。

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建立了绝缘电阻大于10~(13)Ω和温度起伏小于0.1℃的半绝缘砷化镓Hall测量装置。研究了环境温度、湿度、漏电流、数据读取时间、测量电压、样品尺寸等因素对电阻率与迁移率的影响,并讨论了各种因素所引起的测量误差。

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利用GaAs衬底上的InAa薄膜制备的Hall器件,具有灵敏度高(在相同的电子浓度、室温附近灵敏度是GaAs Hall器件的1.5倍),不等位电压温漂小等优点。可用于电流传感器、无刷电机等磁敏传感器中,具有广阔的应用前景。

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于2010-11-23批量导入

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报道了利用InAs外延薄膜制作霍尔器件,通过分子束外延技术在GaAs衬底上生长的InAs薄膜具有较高的迁移率和较好的温度特性。用这种材料制作的霍尔器件在每千欧姆内阻条件下灵敏度与GaAs平面Hall器件相比提高了50%。