Contribution of terahertz waves to near-field radiative heat transfer between graphene-based hyperbolic metamaterials

Hyperbolic metamaterials alternately stacked by graphene and silicon(Si) are proposed and theoretically studied to investigate the contribution of terahertz(THz) waves to near-field radiative transfer. The results show that the heat transfer coefficient can be enhanced several times in a certain THz frequency range compared with that between graphene-covered Si bulks because of the presence of a continuum of hyperbolic modes. Moreover, the radiative heat transfer can also be enhanced remarkably for the proposed structure even in the whole THz range. The hyperbolic dispersion of the graphenebased hyperbolic metamaterial can be tuned by varying the chemical potential or the thickness of Si, with the tunability of optical conductivity and the chemical potential of graphene fixed. We also demonstrate that the radiative heat transfer can be actively controlled in the THz frequency range.     

溅射气压对DC磁控溅射制备AlN薄膜的影响

采用DC反应磁控溅射法,在Si(111)和玻璃基底上成功的制备了AlN薄膜。研究溅射过程中溅射气压对薄膜性能的影响。结果表明:薄膜中原子比N/Al接近于1;当溅射气压低于0.6 Pa时,薄膜为非晶态;当溅射气压不低于0.6 Pa时,薄膜的XRD图中均出现了6方相的AlN(100)、(110)和弱的(002)衍射     

直流磁控溅射制备AlN薄膜的结构和表面粗糙度

采用直流磁控反应溅射法,在Si(111)基底上成功制备了多晶六方相AlN薄膜.研究了溅射过程中溅射气压对薄膜结构和表面粗糙度的影响.结果表明:当溅射气压低于0.6 Pa时,薄膜为非晶态,在傅里叶变换红外光谱中,没有明显的吸收峰;当溅射气压不低于0.6 Pa时,薄膜的X射线衍射图中均出现了六方相的AlN(100)、(110)和弱的(002)衍射峰,说明所制备的AlN薄膜为多晶态,在傅里叶变换红外光谱中,在波数为677 cm-1处有明显的吸收峰;随着溅射气压的增大,薄膜表面粗糙度先减小后增大,而薄膜的沉积速率先增大后减少,且沉积速率较大有利于减小薄膜的表面粗糙度;在溅射气压为0.6 Pa时,薄膜具有最小的表面粗糙度和最大的沉积速率.     

溅射气压对DC磁控溅射制备AIN薄膜的影响

采用DC反应磁控溅射法,在Si(111)和玻璃基底上成功的制备了AIN薄膜.研究溅射过程中溅射气压对薄膜性能的影响.结果表明:薄膜中原子比N/Al接近于1;当溅射气压低于0.6 Pa时,薄膜为非晶态;当溅射气压不低于0.6Pa时,薄膜的XRD图中均出现了6方相的AIN(100)、(110)和弱的(002)衍射峰,说明所制备的AIN薄膜为多晶态;气压为0.6 Pa时对应衍射峰的半高峰宽较小,薄膜的结晶性较好,随着溅射气压的继续增大,薄膜结晶性变差;在不同的溅射气压(0.6-1.0 Pa)下,MN薄膜在250-1000 nm波长范围内的透过率均在82%以上,且随溅射气压的增大略有升高.