Polycrystalline silicon(poly-Si) thin films were prepared on quartz substrates by rapid thermal chemical vapor deposition(RTCVD) system,and their structures were studied by XRD,SEM and TEM,respectively.XRD spectra exh...Polycrystalline silicon(poly-Si) thin films were prepared on quartz substrates by rapid thermal chemical vapor deposition(RTCVD) system,and their structures were studied by XRD,SEM and TEM,respectively.XRD spectra exhibit a single strong(220) diffraction peak,which indicates that the poly-Si films are preferentially <110> oriented.Plane-view SEM images show that the surface of the poly-Si films is composed of large numbers of polygonal pyramid grains with different sizes,and cross-section SEM images further indicate that they are columnar grains with growth direction perpendicular to substrate surface.TEM observation results demonstrate that there are a lot of twin crystals including one-order,two-order and high-order(≥3) twin crystals in the poly-Si films.The above experimental results can not be elucidated by the conventional opinion on growth behavior of poly-Si films prepared by atmosphere pressure chemical vapor deposition(APCVD),but can be explained by the Ino's multiply twinned particles(MTPs) model found in the face centered cubic metal films.According to the above experimental results and Ino's model,we tend to think that nucleation and grain growth of poly-Si films deposited by RTCVD on quartz substrates are based on the formation of MTPs,and then these MTPs form the continuous films in an island growth mode.展开更多
In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal anne...In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal annealing(RTA).The characterizations show that the epitaxial SiGe thin films are single-crystalline with uniform tensile strain and then become polycrystalline after the ion implantation and following RTA.The magnetization measurements indicate that the annealed thin films exhibit Mn concentration-dependent ferromagnetism up to 309 K and the X-ray magnetic circular dichroism characterizations reveal the spin and orbital magnetic moments from the substitutional Mn element.To minimize the influence of anomalous Hall effect,magneto-transport measurements at a high magnetic field up to 31 T at 300 K are performed to obtain the hole mobility,which reaches a record-high value of~1230 cm^(2)V^(-1)s^(-1),owing to the crystalline quality and tensile strain-induced energy band modulation of the samples.The first demonstration of Mn-doped SiGe thin films with roomtemperature ferromagnetism and high carrier mobility may pave the way for practical semiconductor spintronic applications.展开更多
基金supported by the National Natural Science Foundation of China (50802118)National High-Tech Research and Developmen Program of China (2006AA05Z409)+1 种基金China Postdoctor Foundation (20060390741)Natural Science Foundation of Guangdong province (5300577)
文摘Polycrystalline silicon(poly-Si) thin films were prepared on quartz substrates by rapid thermal chemical vapor deposition(RTCVD) system,and their structures were studied by XRD,SEM and TEM,respectively.XRD spectra exhibit a single strong(220) diffraction peak,which indicates that the poly-Si films are preferentially <110> oriented.Plane-view SEM images show that the surface of the poly-Si films is composed of large numbers of polygonal pyramid grains with different sizes,and cross-section SEM images further indicate that they are columnar grains with growth direction perpendicular to substrate surface.TEM observation results demonstrate that there are a lot of twin crystals including one-order,two-order and high-order(≥3) twin crystals in the poly-Si films.The above experimental results can not be elucidated by the conventional opinion on growth behavior of poly-Si films prepared by atmosphere pressure chemical vapor deposition(APCVD),but can be explained by the Ino's multiply twinned particles(MTPs) model found in the face centered cubic metal films.According to the above experimental results and Ino's model,we tend to think that nucleation and grain growth of poly-Si films deposited by RTCVD on quartz substrates are based on the formation of MTPs,and then these MTPs form the continuous films in an island growth mode.
基金supported by the National Key Research and Development Program of China(2017YFB0405702)the National Natural Science Foundation of China(52172272)。
文摘In this work,silicon-germanium(SiGe)thin films are epitaxially grown on Ge substrates by ultra-high vacuum chemical vapor deposition and then doped with Mn element by ion-implantation and subsequent rapid thermal annealing(RTA).The characterizations show that the epitaxial SiGe thin films are single-crystalline with uniform tensile strain and then become polycrystalline after the ion implantation and following RTA.The magnetization measurements indicate that the annealed thin films exhibit Mn concentration-dependent ferromagnetism up to 309 K and the X-ray magnetic circular dichroism characterizations reveal the spin and orbital magnetic moments from the substitutional Mn element.To minimize the influence of anomalous Hall effect,magneto-transport measurements at a high magnetic field up to 31 T at 300 K are performed to obtain the hole mobility,which reaches a record-high value of~1230 cm^(2)V^(-1)s^(-1),owing to the crystalline quality and tensile strain-induced energy band modulation of the samples.The first demonstration of Mn-doped SiGe thin films with roomtemperature ferromagnetism and high carrier mobility may pave the way for practical semiconductor spintronic applications.
