Defects in the topological insulator Bi 2Te 2Se are studied by scanning tunneling microscopy. Small numbers of Te Bi antisite defects are found and are postulated to be the origin of n-type carriers in this tetradymite composition near the n-to-p crossover. Based on this defect chemistry, we design an alternative method for obtaining resistive Bi 2+xTe 2-xSe samples, by the introduction of compensating p-type carriers through Bi Te antisite defects induced by making the material slightly Bi rich. Our resistivity and Hall coefficient measurements of Bi 2+xTe 2-xSe crystals grown by the Bridgeman-Stockbarger method show that the carrier concentration at base temperature is significantly reduced from that of stoichiometric samples. Analysis of the measurements reveals the possible underlying chemical distribution along the boules during growth.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 12 2012|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics