A THEORY ON THE X-RAY-SENSITIVITY OF A SILICON SURFACE-BARRIER DETECTOR INCLUDING A THERMAL CHARGE-DIFFUSION EFFECT - REPLY

The effect of thermal-diffusion charge on the x-ray energy response of silicon surface-barrier (SSB) detectors have generally been ignored; consequently, the SSB response has been believed to be analyzed using the thickness of the depletion layer alone. Our new theory on the SSB x-ray response [J. Appl. Phys. 72, 3363 (1992)] was prepared for addre ssing recent confusion on plasma x-ray analyses using SSB detectors [R ev. Sci. Instrum. 59, 1380 (1988); 61, 693 (1990); 63, 4850 (1992)]. T his approach was made under the assumption of a dominant contribution of the diffusion-charge signal in the vicinity of the x-ray incident l ocation because of the strong reduction of the x-ray produced charge w ithin the thermal-diffusion length. In this report, the comparison bet ween this approximation (having an approximated solution) and the exac t numerical calculation (using an integral form) is carried out. Neces sity and importance of such three-dimensional treatments for the data analyses as well as the design of multichannel semiconductor-array det ectors developed for plasma x-ray tomography diagnostics are highlight ed. Furthermore, for the total diffusing-charge amount, the calculated results from our theory and the values using the comment from Donolat o agree well within the accuracy of 1 %.