Question

Suppose we have an ideal n-channel, silicon MOSFET at room temperature with a silicon oxide thickness of 100 nm for the gate oxide, NA = 5 x 10¹⁶ cm³, and a channel with a width 5 um and length of 1 um, and an effective mobility of 1400 cm/Vs. The dielectric constant (Kₒₓ) of SiO₂ is 3.9, dielectric constant (Ks) of Si is 11.7. Compute the following: For Vos = 100 mV < Vossat, what is the current when VG is 3.5 V?

Answer 1

Without the threshold voltage (Vt) for the n-channel silicon MOSFET, we cannot calculate the specific current when VG is 3.5 V; more information is required to solve the problem.

Step-by-step explanation:

To compute the current when VG is 3.5 V for an n-channel silicon MOSFET with the given parameters, we use the linear mode operation equation because the provided VDS (100 mV) is less than VDSSat (the drain-source saturation voltage).

The linear mode current equation is:

ID = (μnCox/L)W(VGS - Vt) - (μnCox/2L)WV²DS

where μn is the electron mobility, Cox is the gate oxide capacitance per unit area, W and L are the width and length of the channel, respectively, VGS is the gate-source voltage, Vt is the threshold voltage, and VDS is the drain-source voltage.

The gate oxide capacitance per unit area (Cox) is calculated using the equation:

Cox = (ε0εr)/d

Here, ε0 is the permittivity of free space, εr is the relative permittivity (dielectric constant) of silicon dioxide, and d is the thickness of the SiO2 layer.

However, to find the current, we need the threshold voltage Vt, which is not provided. Since the provided parameters don't allow us to calculate the exact current without knowing Vt, we cannot provide a specific numerical answer.