掺杂对多层Ge/Si(001)量子点光致发光的影响

Effect of doping on the photoluminescence of multilayer Ge quantum dots deposited on Si(001) substrate

利用超高真空化学气相沉积设备,在Si(001)衬底上外延生长了多个四层Ge/Si量子点样品.通过原位掺杂的方法,对不同样品中的Ge/Si量子点分别进行了未掺杂、磷掺杂和硼掺杂.相比未掺杂的样品,磷掺杂不影响Ge/Si量子点的表面形貌,但可以有效增强其室温光致发光;而硼掺杂会增强Ge/Si量子点的合并,降低小尺寸Ge/Si量子点的密度,但其光致发光会减弱.磷掺杂增强Ge/Si量子点光致发光的原因是,磷掺杂为Ge/Si量子点提供了更多参与辐射复合的电子.

Four-bilayer Ge quantum dots （QDs） with Si spacers were epitaxially grown on Si（001） substrates by means of ultrahigh vacuum chemical vapor deposition. In two samples, Ge QDs were in situ doped with phosphorus or boron, separately. Surface morphology and room temperature photoluminescence （PL） of multilayer Ge/Si QDs wer studied. Compared with the undoped Ge QDs, phosphorus-doping did not change the morphology of Ge QDs, enhanced PL wer observed from the phosphorus-doped Ge QDs. But reduction of Ge QDs density and PL intensity wer observed from the boron-doped Ge QDs. The intensity enhancement of PL could be attributed to the sufficient supply of electrons in Ge QDs for radiative recombination.