Carrier Mobility up to 106 cm2 V-1 s-1 Measured in Single-Crystal Diamond by the Time-of-Flight Electron-Beam-Induced-Current Technique

Diamond is a very promising material for various applications, and understanding its basic properties is key for the development of future devices. In particular, the low-field mobility of holes has never been measured below & SIM; 80 K in ultrapure diamond. In order to measure this mobility, we developed an innovative time-of-flight electron-beam-induced-current technique. A 1 ns pulsed electron beam was made to impact the diamond semiconductor, inducing charge-carrier creation and motion through the 546 -& mu;m thick bulk diamond, under the influence of an applied electric field. The resulting signal was analyzed using the transient-time technique. Thus, the velocity of electrons and holes was assessed as a function of the temperature from 13 to 300 K and as a function of the electric field with values ranging from 1.5 to 9200 V cm-1. A low-field mobility value of 1.03 & PLUSMN; 0.05 x 106 cm2 V-1 s-1 was measured for holes at 13 K, demonstrating that diamond is a suitable material to transport charge carriers in a ballistic regime at a scale of 10 & mu;m.