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Preliminary results on 16 CM{sup 2}, position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 {times} l0{sup 6} s{sup {minus}1} is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 {mu}m to 1200 {mu}m. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed.

We demonstrate simultaneous high energy resolution (rms≃800 eV) measurements of ionization and phonons created by particle interactions in a semiconductor crystal of macroscopic size (60 g germanium) at 25 mK. We present first studies of charge collection at biases below 1 V/cm, and find that, contrary to commonly held opinion, the full recoil energy of particle interactions is recovered as phonons when charge trapping is negligible. We also report an unanticipated correlation between charge collection and phonon energy at very low bias, and discuss this effect in terms of charge trapping

We have fabricated a 4 cm long, position-sensitive silicon drift detector using high purity, p-type silicon as the starting material. In this paper, we describe the double-sided planar process used to fabricate the detectors and the strategy used to suppress surface carrier inversion due to the presence of fixed positive charge at the Si-SiO/sub 2/ interface. The key issue in optimizing the fabrication process has been to minimize leakage currents and maximize breakdown voltages. Preliminary tests show that a drift signal can be measured across the entire length of the detectors and that the transit time of the holes varies linearly with the position of the induced charge signal. >

Results on the characterization of the electrical properties of amorphous silicon films for the three different growth methods, RF sputtering, PECVD, and LPCVD are reported. The performance of these a-Si films as heterojunctions on high resistivity p-type and n-type crystalline silicon is examined by measuring the noise, leakage current and the alpha particle response of 5 mm diameter detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. The results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated.

The authors studied the use of neutron-transmutation-doped (NTD) Ge thermistors as phonon sensors at dilution refrigerator temperatures. In addition to measuring their thermal and electrical properties the authors observed pulses generated by X-rays incident on a thermistor thermally well clamped to a heat sink. It is found that during these pulses the lattice temperature of the thermistor apparently does not change. This is interpreted as evidence of a strong coupling between the high-energy phonons generated by the interactions and the charge carriers in the thermistor. The phonons appear to be absorbed within a fraction of a millimeter. It is concluded that the thermistors have several desirable properties for a high-energy phonon sensor. It remains to be seen, however, if a composite detector consisting of a large crystal and attached phonon sensors can be developed. >