Laterally-graded doping into ge-on-insulator by combination of ion-implantation and rapid-melting growth

Ge-on-insulator (GOI) having laterally-graded doping-profiles is essential to formation of functional-devices such as high-efficiency thermo-electric devices. To achieve this, rapid-melting growth of a-Ge strips implanted with P ions is investigated under a dose range of 1 × 10¹²-2 × 10¹⁵ cm-2. For dose over 1 × 1014 cm-2, grown-Ge layers show n-type conduction. Moreover, for dose of 2 × 10¹⁵ cm-2, a laterally-graded doping-profile (∼8 × 1015 cm^-3/μm) is achieved in the grown region (growth-distance: 0-300 μm) by P segregation during the melt-back process. The graded doping-profile generates electric-fields of -0.6 V/cm, which can be increased by decreasing strip-length. This technique is expected to facilitate integration of functional-devices on Si-platform.