We investigate the electronic structures of one and two monolayer iron phthalocyanine （FePc） molecules on Au（111） surfaces. The first monolayer FePc is lying flat on the Au（111） substrate, and the second monolay...We investigate the electronic structures of one and two monolayer iron phthalocyanine （FePc） molecules on Au（111） surfaces. The first monolayer FePc is lying flat on the Au（111） substrate, and the second monolayer FePc is tilted at -15° relative to the substrate plane along the nearest neighbour [101] direction with a lobe downward to the central hole of the unit cell in the first layer. The structural information obtained by first-principles calculations is in agreement with the experiment results. Furthermore, it is demonstrated that the electronic structures of FePc molecules in one-monolayer FePc/Au（111） system are perturbed significantly, while the electronic structures of FePc molecules in the second monolayer in two-monolayer FePc/Au（111） system remain almost unchanged due to the screening of the buffer layer on Au（111）.展开更多
A silicon carbide （SIC） based metal semiconductor field effect transistor （MESFET） is fabricated by using a standard SiC MESFET structure with the application of a dual p-buffer layer and a multi-recessed gate to ...A silicon carbide （SIC） based metal semiconductor field effect transistor （MESFET） is fabricated by using a standard SiC MESFET structure with the application of a dual p-buffer layer and a multi-recessed gate to the process for an S-band power amplifier. The lower doped upper-buffer layer serves to maintain the channel current, while the higher doped lowerbuffer layer is used to provide excellent electron confinement in the channel layer. A 20-mm gate periphery SiC MESFET biased at a drain voltage of 85 V demonstrates a pulsed wave saturated output power of 94 W, a linear gain of 11.7 dB, and a maximum power added efficiency of 24.3% at 3.4 GHz. These results are improved compared with those of the conventional single p-buffer MESFET fabricated in this work using the same process. A radio-frequency power output greater than 4.7 W/mm is achieved, showing the potential as a high-voltage operation device for high-power solid-state amplifier applications.展开更多
研究了引入有机小分子尿素(urea)作为阴极缓冲层的以P3HT∶PCBM为活性层的体异质结聚合物太阳能电池(BHJ-PSCs)。通过溶液旋涂法制备尿素层,并且以不同的旋涂速度得到不同厚度的尿素。在模拟的标准太阳光(100 m W/cm2)照射下,以3000 r/...研究了引入有机小分子尿素(urea)作为阴极缓冲层的以P3HT∶PCBM为活性层的体异质结聚合物太阳能电池(BHJ-PSCs)。通过溶液旋涂法制备尿素层,并且以不同的旋涂速度得到不同厚度的尿素。在模拟的标准太阳光(100 m W/cm2)照射下,以3000 r/min的转速旋涂尿素得到的器件取得了9.15 m A/cm2的短路电流密度,此时对应的能量转换效率较不加尿素层时的效率提高了20%,由2.8%增加到3.36%。原子力显微镜的测试表明,尿素层的引入改善了有机层和Al电极的接触。暗态J-V曲线的研究以及外量子效率的分析说明尿素层的引入抑制了载流子的复合,促进了载流子的传输与收集。尿素分子中氧原子上的孤对电子和Al发生强烈的化学反应,有效保护了活性层免受蒸镀的Al原子因注入带来的破坏,这种保护行为减少了载流子的复合,提高了器件的性能。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.10774176)the National Basic Research Program of China (Grant Nos.2006CB806202 and 2006CB921305)the Shanghai Supercomputing Center,Chinese Academy of Sciences
文摘We investigate the electronic structures of one and two monolayer iron phthalocyanine （FePc） molecules on Au（111） surfaces. The first monolayer FePc is lying flat on the Au（111） substrate, and the second monolayer FePc is tilted at -15° relative to the substrate plane along the nearest neighbour [101] direction with a lobe downward to the central hole of the unit cell in the first layer. The structural information obtained by first-principles calculations is in agreement with the experiment results. Furthermore, it is demonstrated that the electronic structures of FePc molecules in one-monolayer FePc/Au（111） system are perturbed significantly, while the electronic structures of FePc molecules in the second monolayer in two-monolayer FePc/Au（111） system remain almost unchanged due to the screening of the buffer layer on Au（111）.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61076072)
文摘A silicon carbide （SIC） based metal semiconductor field effect transistor （MESFET） is fabricated by using a standard SiC MESFET structure with the application of a dual p-buffer layer and a multi-recessed gate to the process for an S-band power amplifier. The lower doped upper-buffer layer serves to maintain the channel current, while the higher doped lowerbuffer layer is used to provide excellent electron confinement in the channel layer. A 20-mm gate periphery SiC MESFET biased at a drain voltage of 85 V demonstrates a pulsed wave saturated output power of 94 W, a linear gain of 11.7 dB, and a maximum power added efficiency of 24.3% at 3.4 GHz. These results are improved compared with those of the conventional single p-buffer MESFET fabricated in this work using the same process. A radio-frequency power output greater than 4.7 W/mm is achieved, showing the potential as a high-voltage operation device for high-power solid-state amplifier applications.
文摘研究了引入有机小分子尿素(urea)作为阴极缓冲层的以P3HT∶PCBM为活性层的体异质结聚合物太阳能电池(BHJ-PSCs)。通过溶液旋涂法制备尿素层,并且以不同的旋涂速度得到不同厚度的尿素。在模拟的标准太阳光(100 m W/cm2)照射下,以3000 r/min的转速旋涂尿素得到的器件取得了9.15 m A/cm2的短路电流密度,此时对应的能量转换效率较不加尿素层时的效率提高了20%,由2.8%增加到3.36%。原子力显微镜的测试表明,尿素层的引入改善了有机层和Al电极的接触。暗态J-V曲线的研究以及外量子效率的分析说明尿素层的引入抑制了载流子的复合,促进了载流子的传输与收集。尿素分子中氧原子上的孤对电子和Al发生强烈的化学反应,有效保护了活性层免受蒸镀的Al原子因注入带来的破坏,这种保护行为减少了载流子的复合,提高了器件的性能。
