InGaN/GaN multiple quantum well for superfast scintillation application: Photoluminescence measurements of the picosecond rise time and excitation density effect

We report the study of the fast rise time and decay time in the ps time scale of the excitonic luminescence of a multiple quantum well (MQW) heterostructure of InGaN/GaN, including the excitation density effect. These structures were proposed as ultrafast scintillators for soft X-ray detectors and particle beam diagnostics. Measurements were carried out with a Hadland Imacon 500 streak camera following excitation of the sample by laser pulses of few tens of mu J at 266 nm and 400 nm, with pulse duration less than 200 fs. The rise time of the detected MWQ luminescence was less than 10 ps, with a possible contribution from the detection system and signal collection geometry. The calibration and the signal processing techniques employed to fully exploit the time resolution of the detection system are also described.