Pixel device based on a quantum well: Preliminary results on gate dielectrics

The development of pixel arrays close to the interaction point in large detector systems used in high energy physics require high radiation hardness for the pixels and their readout. A pixel device based on a quantum well, called the DoTPiX uses a sensing n-channel MOS device with a control gate. A buried Ge layer acts as a current modulation gate, which localize holes generated by impinging particles. The DotPIX buried Ge gate is obtained by low temperature epitaxial growth of Ge on Si. We have started to study the different ways to achieve these prerequisites: the need for a low temperature budget to reduce the Ge and Si intermixing, which may be detrimental to the DoTPiX operation. The use of Si thermal oxide is investigated together with that of deposited oxide (Hafnium Oxide for example), which differs from the Silicon Dioxide. The possibility of a combination of thermal silicon dioxide and deposited oxides opens another possibility in this study.