P-type one-sided hexagonal spiral drift detectors

A new P-type Drift Detector (PDD) with one-sided hexagonal spiral shaped cathodes around the center anode has been designed, simulated, constructed and tested. Large arrays of drift cells are required for the application. The large number of cells forces the design of the drift cell with a minimal number of bonds per cell. The presented design creates the drift field by the spiral-based voltage divider. Moreover, the leakage current created at the depleted part of the detector surface is also collected without an external connection to the cell. The current is collected directly on the inner terminal of the divider. The lithographic processes of the wafer are done only on one side resulting in a much faster fabrication. For the first time, the design makes an active usage of the positive charge in the oxide as a rectifying junction on p-type silicon.