Si衬底上InP纳米线的晶体结构和光学性质

The Crystal Structure and Optical Properties of InP Nanowires Grown on Si Substrate

采用金属有机化学气相沉积技术,利用自催化法,在Si(100)、(111)衬底上成功生长了InP纳米线。利用扫描电镜观察样品表面,在Si(100)、(111)衬底上生长的纳米线形貌相似,纳米线面密度不同。利用X射线衍射和透射电镜研究纳米线的生长取向和晶体结构,结果显示纳米线具有闪锌矿结构,生长方向〈111〉,并且具有层状孪晶结构。与InP体材料相比,纳米线的光致发光峰位蓝移,半峰全宽增大,拉曼散射TO和LO峰向低波数频移,频移随激发光功率减弱而减小。

Self-catalyzed InP nanowires were grown on Si（100） and Si（111） substrates by metal-organic chemical vapor deposition.Morphology,crystal structure,and optical properties of the nanowires were investigated.Using scanning electron microscope（SEM）,we found that the morphology of the InP nanowires grown on Si（100） was similar with that of the InP nanowires grown on Si（111）.The only difference between them was the density of the nanowires.Most nanowires are long and straight;the angles between the nanowires and the Si substrate are diverse.This was attributed to the native oxide on Si substrates.The X-ray diffraction results showed that two peaks of InP（111） and InP（220） was able to be seen in the spectra.Two more peaks of InP（200） and InP（311） were observed if we continue to supply PH3 for 15 min after the nanowires growth for 7 min.The InP（220）,InP（311）,and InP（200） originated from InP crystal on the tip of the nanowires.Only the InP（111） originated from the InP nanowires.The transmission electron microscope（TEM） and transmission electron diffraction（TED） results showed that the nanowires exhibit zinc-blende（ZB） crystal structure;the main growth direction of the nanowires was 〈111〉;the nanowire has twin stacking faults.Temperature-dependent photoluminescence（PL） spectra of Fe doped InP substrate and InP nanowires grown on Si（100） were measured in the rages of 80 to 300 K.The PL peak at 1.425 eV for 80 K,for InP nanowires,shifted to 1.379 eV at 300 K,while the PL peak energy of InP substrate was 1.413 eV and 1.349 eV,respectively.The reasons for the blue-shift of the nanowires could be the existence of twin stacking faults.Due to laser-induced heating,the TO and LO phonon peaks of the nanowires revealed downshift and asymme-tric broadening compared with those of bulk InP at room temperature.