Ray Chin Chong Yap, Hong Li, Wai Leong Chow, Cong Xiang Lu, Beng Kang Tay and Edwin Hang Tong Teo
The mechanisms of p-to-n conversion and vice versa in unipolar graphene field-effect transistors (GFETs) were systematically studied using Raman spectroscopy. Unipolar p-type GFETs are achieved by decorating the graphene surface with a thin layer of titanium (Ti) film, resulting in a Raman D peak. The D peak is observed to recover by annealing the GFET in nitrogen ambient followed by silicon nitride (Si 3 N 4 ) deposition, suggesting that the Ti adatoms are being partially removed. Furthermore, unipolar n-type GFETs are obtained after the passivation on p-type GFETs. The threshold voltage of the n-type GFET is dependent on the thickness of the Si 3 N 4 layer, which increases as the thickness decreases. A comparison between the Si 3 N 4 and SiO 2 passivation layers shows that SiO 2 passivation does not convert the GFET into n-type graphene, which identifies the significance of ammonia (NH 3 ) for ...
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The mechanisms of p-to-n conversion and vice versa in unipolar graphene field-effect transistors (GFETs) were systematically studied using Raman spectroscopy. Unipolar p-type GFETs are achieved by decorating the graphene surface with a thin layer of titanium (Ti) film, resulting in a Raman D peak. The D peak is observed to recover by annealing the GFET in nitrogen ambient followed by silicon nitride (Si 3 N 4 ) deposition, suggesting that the Ti adatoms are being partially removed. Furthermore, unipolar n-type GFETs are obtained after the passivation on p-type GFETs. The threshold voltage of the n-type GFET is dependent on the thickness of the Si 3 N 4 layer, which increases as the thickness decreases. A comparison between the Si 3 N 4 and SiO 2 passivation layers shows that SiO 2 passivation does not convert the GFET into n-type graphene, which identifies the significance of ammonia (NH 3 ) for ...
Link to full article
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