Lifetime and spin relaxation time measurements of micro-fabricated GaAs tips

Circularly polarized light pumped GaAs tip is expected for application to a spin-polarized electron source, and, development of spin-polarized scanning tunneling microscope (SP-STM) using the GaAs tip has recently been attempted by some research groups. So far spin dependent tunneling current has been detected for the magnetic sample in SP-STM using the GaAs tip. However, there was very little information concerning to lifetime and spin relaxation time of electrons in the GaAs tips. In this study, time-resolved photoluminescence (TR-PL) from GaAs microtips was measured to evaluate lifetime and spin relaxation time.