Native transistor
Native transistor is the rare variety of the MOSFET. Most common is the n-channel native transistor. Historically, it was referred to the MOSFET without specially grown oxide, only natural thin oxide film formed over silicon during processing of other layers. As in 2008, native (natural) MOSFET is the transistor with nearly zero threshold voltage. Native NMOS have a niche applications in low-voltage Opamp and in low-voltage digital memory, there it function as the weak pull-down. It also used in low-voltage interface circuits.
The main disadvantages if the native transistors is the larger size due additional doping mask and so lower transconductance. Typical minimal size of the native NMOS gate is 2-3 times longer and wider then standard threshold voltage transistor. The price of chip including native transistors is also increased because of the additional doping operations.