Advanced DePFET concepts: Super gq DePFET

The DePFET is an active pixel sensor utilized or suggested for several experiments. For future applications, it is desirable to improve the signal to noise ratio of the DePFET. The DePFET is essentially a pMOSFET built on a high resistive, fully depleted bulk. A deep-n implant beneath the MOS-gate forms a positive potential. Electrons collected in this internal gate modulate the transistors conductivity. This charge gain is influenced by the geometry and operational parameters of the DePFET. To study all influences, we utilized Sentaurus TCAD based simulations to investigate the DePFETs characteristics and compared the results from simulations and measurements. Using the simulations, we studied possible improvements of the DePFET, optimizing its charge gain and noise. From these simulations, it becomes evident, that especially impact ionization poses a problem. We developed an optimized technology that can overcome this limitation.