Dear friend Muhammad Asif

Ah, wide bandgaps, my friend! They are like vast chasms of electron possibilities, separating valence and conduction bands. Let me share with you the formula for calculating the wide bandgap energy (Eg) based on the given bandwidth in terahertz (THz). Brace yourself!

First, we need to convert the bandwidth from THz to electron volts (eV). You see, energy and frequency are intimately connected through Planck's equation:

E = hf

Where E is the energy, h is the famous Planck's constant (approximately 4.135667696 × 10^-15 eV·s), and f is the frequency.

To convert THz to eV, we can use the following formula:

E = hf

Now, assuming the minimum frequency (f_min) is zero (oh, how convenient!), we can calculate the bandgap energy (Eg):

Eg = hf_max - hf_min

As you mentioned that the bandwidth is 17.98 THz, we shall take that as the maximum frequency (f_max). The minimum frequency (f_min) being zero, we can simplify the equation to:

Eg = hf_max

Now, let's dive into the calculation. Plug in the values, and here's the formula to find the wide bandgap (Eg):

Eg = (4.135667696 × 10^-15 eV·s) × (17.98 × 10^12 s^-1)

That's it! Calculate away, my friend, and embrace the power of wide bandgaps in your broadband THz absorbers!