DEPLETION AND PINCHOFF

A JFET works because the voltage at the gate causes an electrical field that interferes, more or less, with the flow of charge carriers along the channel. As the drain voltage E_D increases, so does the drain current I_D, up to a certain level-off value. This is true as long as the gate voltage E_G is constant and is not too large. As E_G increases (negatively in an n channel or positively in a p channel), a depletion region develops within the channel.
Charge carriers cannot flow in the depletion region, so when there is such a region, they must pass through a narrowed channel. The larger E_G becomes, the wider the depletion region gets, and the more constricted the channel becomes. If E_G is high enough, the depletion region completely obstructs the flow of charge carriers, and the channel cannot conduct current at all. This condition is known as pinchoff. It is like pressing down on a garden hose until the water can’t flow.

مواضيع ذات صلة

الحجم النووي Nuclean Size

ربوتات النانو (Nanorobots)

تلسكوبات الأشعة تحت الحمراء والسينية

المقاومة الداخلية المرتفعة لبطارية ليثيوم-ايون

أهمية تقنية النانو (Importance of nanotechnology)

متسعات المرشح على التوالي Filter Capacitors in series

أشباه الموصلات

ظاهرة الحفز الضوئي

مكشاف أشباه الموصلات Semiconductor detector

ميكروسكوبات السليكون

تأثيرات الدفيئة وثقب طبقة الأوزون

مخطط الطاقة لوصلة ال PN