What is the difference between an enhanced MOS transistor and a depleted MOS transistor?

What is the difference between an enhanced MOS transistor and a depleted MOS transistor?

Field-effect transistor are divided into JFET (JFET) and insulated gate Field-effect transistor (MOS).

Divided into N channel and P channel according to channel material type and insulation grid type; According to the conduction mode: depletion type and enhancement type, JFET are depletion type, and insulated gate type Field-effect transistor have both depletion type and enhancement type.

Field effect transistor can be divided into junction field-effect transistors and MOS field-effecttransistor, while MOS field-effect transistor are further divided into N-channel depletion and enhancement types; There are four categories of P-channel depletion and enhancement.

Insulated gate Field-effect transistor is composed of metal, oxide and semiconductor, so it is also called metal oxide semiconductor Field-effect transistor, or MOS Field-effect transistor for short.

The operating principle of insulated gate Field-effect transistor (taking N-channel enhanced MOS Field-effect transistor as an example) is to use UGS to control the number of "induced charges", so as to change the condition of conductive channels formed by these "induced charges", and then to control the drain current. When manufacturing pipes, a large number of positive ions are present in the insulation layer through the process, so a large amount of negative charges can be induced on the other side of the interface. These negative charges connect the N region of high permeability impurities, forming a conductive channel, and even at VGS=0, there is a large drain current ID. When the gate voltage changes, the amount of induced charge in the channel also changes, and the width of the conductive channel also changes accordingly. Therefore, the drain current ID changes with the change of the gate voltage.

Field-effect transistor works in two ways: the so-called enhancement or depletion, mainly refers to the inversion layer in the MOS transistor. If the inversion layer does not exist when there is no power supply, and the voltage is applied to a certain extent before the inversion layer appears (when the gate voltage is zero, the drain current is also zero, and a certain amount of gate voltage must be applied before the drain current can occur), this is enhancement. On the contrary, if the inversion layer exists from the beginning, as the voltage increases or decreases, the inversion layer will increase or decrease, and (when the gate voltage is zero, there is a large drain current) this is depletion.