本篇論文我們在石墨烯-砷化鎵/鋁砷化鎵異質結構混成元件研究石墨烯迴旋輻射，目前石墨烯迴旋輻射是個在實驗中尚未被成功觀測到的題目，我們採用化學氣相沉積法製備的石墨烯覆蓋在砷化鎵/鋁砷化鎵異質結構表面，而二維電子氣則位於表面下105 nm。我們藉由外加1 T垂直於元件的磁場，使石墨烯藍道能階n = 0 與 n = 1 能量差Egr =37meV，當以大於Egr /2e的電壓通過石墨烯時，非平衡載子產生，而迴旋輻射現象在汲極與源極的熱點(hot-spot)區甚至是通道區間發生。石墨烯的迴旋輻射探測上，我們調變石墨烯藍道能級對應到砷化鎵光聲子(LO、TO )能量下，藉由吸收迴旋輻射，位於砷化鎵層的二維電子氣環境溫度將被提升，我們期望能藉由這種電阻熱效應來探測到石墨烯迴旋輻射。
　　
　　實驗中我們藉由免液氦系統冷卻樣品，並調變量測溫度由1.4 K到110K且最大外加磁場達到8 T，石墨烯與二維電子氣的歐姆接觸在元件上不相接觸，溫度80 K的二維電子氣磁聲子共振訊號明確指出LO聲子在二維電子氣磁阻量測中的影響。我們採用兩種元件幾何圖形設計也利用兩種探測機制來探測迴旋輻射訊號，而在我們的量測條件下，訊號大小進入了雜訊範圍，所以我們並沒有清楚量測到石墨烯迴旋輻射現象。

　　我們認為在本實驗的想定中無法測得該訊號的原因是石墨烯迴旋輻射強度遠比期望的小，或者是磁阻變化的量測上探測感度不足。在未來的工作上我們建議提升石墨烯的品質或者採用感度更好的探測機制或元件。

We investigate cyclotron emission (CE) of graphene by a graphene/GaAs-AlGaAs heterostructure hybrid device. To date, this challenging subject - CE of graphene- has not been successfully observed. We employ chemical vapor deposited graphene on top of GaAs-AlGaAs heterostructure with two dimensional electron gas (2DEG) 105 nm beneath the surface. To generate CE, we apply perpendicular magnetic field to the device up to 1 T, giving rise Landau level energy spacing E gr between n = 0 to n = 1 of graphene about 37 meV. While the applied source-drain bias on graphene larger than E gr/2e, nonequilibrium carriers would be generated, and CE occurs at the hot-spot corners or even within the bulk regime. To detect CE, we consider Egr actually is matched to the phonon energy (LO and TO phonons) of GaAs crystal. By absorbing CE, 2DEG in GaAs layer will be heated up and we expect this kind bolometric effect can be measured by the change of the longitudinal resistance of 2DEG.
The device is cooled down in a cryostat with varying temperature from 1.4 K to 110 K and magnetic field up to 8 T. Electrical contacts were made separately to contact Graphene and 2DEG. Clear magnetophonon resonances of 2DEG are observed at 80 K, supporting the role of LO phonon in magnetoresistance. We adopt two different device designs and use two different modulation ways to catch CE signals. We do not find a clear signal of CE in graphene, although the noise level seemly becomes larger in the target conditions.
The absence of CE may suggest that radiation signal is much weaker than one expected or the magnetoresistance of 2DEG is not sensitive enough for the present experiment. For future works, we suggest to improve the quality of graphene and to adopt more sensitive detective mechanism.

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