Interface pn junction arrays with high yielded grown p-Si microneedles by vapor–liquid–solid method at low temperature

Fabrication of pn junction arrays with highly successful grown n-Si microneedles by using low temperature VLS method

“…01 µm; these penetrations are compatible with microneedle length and substrate thickness (500 ± 50 µm). Compared to the previous work [25], the depletion width in this work is smaller, this is because, the impurity concentration level, in the present work, is higher than the concentration level in the previous work [25]. That is, with the increase of impurity concentration, the depletion width decreases.…”

“…Figure 12 presents the current-voltage behavior of such an interface pn junction formed with n-Si microneedle of 54.8 µm tall and diameter of 3.1 µm. Compared to pn junction with p-Si microneedle [25], the forward current of pn junction with n-Si microneedle is found much larger, this is because, n-Si microneedle is much more conductive than p-Si microneedle. Therefore, pn junction with n-Si microneedle, realized in this work, would be more suitable for sensors and bio applications.…”

“…Figure 9 shows the variation of conductivity of n-Si microneedle with doping variation; the conductivity increases from 14 Ω −1 cm −1 to 167 Ω −1 cm −1 for the increase of PH 3 /Si 2 H 6 ratio from 1 to 10 ppt. For the same range of doping ratio, the conductivity of p-Si microneedle was from 0.0001 Ω −1 cm −1 to 2 Ω −1 cm −1 [25]; that is, n-Si microneedle is much more conductive than p-Si microneedle. the device with n-Si microneedle would be more suitable for sensors, bio-applications, etc; lecting and processing bio signals.…”

“…Therefore, we worked for applying VLS grown doped Si microneedles for fabricating active devices. Afterwards, we fabricated active device (diode) with p-Si microneedles [25]. To fabricate further sophisticated devices like bipolar junction transistor (BJT), metal oxide semiconductor field effect transistor (MOSFET) using Si microneedles, in addition to p-Si microneedles, we also need n-Si microneedles.…”

“…A comparative study was carried out between p-type and n-type Si microneedles grown by VLS [28]. From our experience of working in this area we found that VLS growth success with p-type doping was very high; p-Si microneedle arrays, with 100% yield, could be grown frequently with different growth conditions at different levels of boron doping [24,25]; but n-Si microneedles could not be fabricated with such high success. As far as we know, there is no report on 100% yield VLS growth of n-Si needle in micro range.…”