Electronic Devices - Semiconductors - Discussion

In forward bias barrier potential is decrease if temp increase, because barrier potential is the value of depletion width.

Vd~nVtlog(If/Is)

Is(leakage current is more sensitive to temperature than Vt(thermal voltage)...If increases, log function decreases therefore forward voltage decreases.

In fb region characteristics of diode shifts towards left by rise in temp therefore the barrier potential decreases.

It decreases because as the temperature increases, electrons get excited and starts moving across the barrier. This results in decrease of barrier potential.

Vbi = kT/e ln(NaNd/Ni^2)
since, NaNd < Ni^2
which makes ln(NaNd/Ni^2) a negetive value. When temperature increases the value of Vbi becomes more negetive or we can say its value decreases.

According to energy band theory if temperature increases the vbi built in potential decreases. Why because due to average thermal energy kt increases more number of carriers will go into conduction band or diffusion length decreases. Or by taking potential hill negative for p side in a p-n junction it will prevent majority carriers movement from p to n side. As temp increases applied vtg increases to nullify vbi neg in p side and holes will now going to higher to lower. Diffusion process may increases due to smaller energy gap.

@ramandeep.

Barrier potential decreases with increase in temp.

From expression v. = kt/e loge NaNd/Ni^2. Itt appears barrier potential increases but due to increase in temp. There is more thermally generated charge carriers. Hence value of Ni in the expression increases. Hence net effect is that barrier potential decreases. We also have a relation change in barrier potential for silicon is -2. 5mv /c rise in temp.

v.=kt loge NaNd/Ni^2
i.e when temp inc barrier potential inc

As we increase the temperature the gap b/w the pn junction decreases so there should be breakage/decrease of barrier potential.

As the temparature increases the enrgy gap between valence band and conduction band decreases and hence barrier potential may also decrease.