Single-hole tunneling into a strain-induced SiGe quantum ring

Abstract

We have observed single-hole tunneling and Coulomb blockade in the resonant tunneling characteristics of an ultrasmall Si/SiGe strained vertical quantum dot. The current steps near the tunneling threshold are due to tunneling of the holes from the emitter to the doubly degenerate ground state of the strain-induced quantum ring in the vertical quantum dot, and the spacing of the steps gives the charging energy of the quantum ring. When a magnetic field is applied parallel to the tunneling direction, the evolution of the single-hole tunneling features reveals a cusp arising from the angular-momentum transition of the single-particle ground state of the quantum ring in the magnetic field.

Self-assembled nanorings in Si-capped Ge quantum dots on (001)Si

“…[12][13][14] In view of the transient nature of the nanorings in this work, the Si/Ge ringlike islands captured by rapid cooling of the samples with appropriate amount of Si capping in this work shall provide a good framework to investigate the properties of unconventional SiGe quantum structures. 15,16 Figures 3͑a͒, 3͑b͒, and 3͑c͒ show XTEM images of the uncapped domes, truncated pyramids and nanorings, respectively. It is evident that Ge QDs reduced its heights with the increase of Si coverage.…”

Room-Temperature Observation of Size Effects in Photoluminescence of Si$_{0.8}$Ge$_{0.2}$/Si Nanocolumns Prepared by Neutral Beam Etching

“…Indeed, in the case of Si 0:8 Ge 0:2 layers formed on Si, the hole trapping energy in the fully relaxed case is $30 meV less than that in the fully strained case. 23) Therefore, the blue shift of $30 meV is expected when the strain in Si 0:8 Ge 0:2 QDs is removed completely. This $30 meV is comparable to the blue shift of $32 meV observed between 24-and 18-nm-average-diameter nanocolumns.…”