INTRINSIC CARRIER CAPTURE TIME IN DEEP-ETCHED QUANTUM-BOX (70 NM DIAMETER) LASERS AT LOW-TEMPERATURE - AN INDICATION OF EXTREMELY HIGH QUANTUM CAPTURE EFFICIENCY

In this letter we report the measurement result of intrinsic carrier c apture time in deep-etched quantum-box (70 nm diameter) lasers at low temperature (2 and 77 K). In order to investigate intrinsic carrier ca pture and relaxation mechanism, we have to rule out the contribution o f the geometry factor and derive the local quantum capture time, For t his purpose. lasers with the same box size (70 nm) but different box d ensities, that are arranged as two-dimensional periodic arrays for dis tributed feedback operations are prepared and measured. We find that t he quantum capture time of the box lasers determined at 2 and 77 K is only about 2.4 ps and is smaller than the corresponding value of the q uantum-well lasers, This is a direct experimental indication of the ex istence of an efficient channel for carrier capture and relaxation in the quantum-box system investigated. (C) 1997 American Institute of Ph ysics.