Low Gain Avalanche Detectors (LGAD) for particle physics and synchrotron applications

A new avalanche silicon detector concept is introduced with a low gain in the region of ten, known as a Low Gain Avalanche Detector, LGAD. The detector's characteristics are simulated via a full process simulation to obtain the required doping profiles which demonstrate the desired operational characteristics of high breakdown voltage (500 V) and a gain of 10 at 200V reverse bias for X-ray detection. The first low gain avalanche detectors fabricated by Micron Semiconductor Ltd are presented. The doping profiles of the multiplication junctions were measured with SIMS and reproduced by simulating the full fabrication process which enabled further development of the manufacturing process. The detectors are 300 mu m thick p-type silicon with a resistivity of 8.5 k Omega cm, which fully depletes at 116V. The current characteristics are presented and demonstrate breakdown voltages in excess of 500V and a current density of 40 to 100 nAcm(-2) before breakdown measured at 20 degrees C. The gain of the LGAD has been measured with a red laser (660 nm) and shown to be between 9 and 12 for an external bias voltage range from 150V to 300V.