When a diode is Zero biased (no external energy source is applied), then which of the following has the highest barrier potential?
A. Germanium
B. Silicon
C. Germanium Arsenide
D. All of them have same barrier potential

Hint:A diode is a semiconductor chip that functions as a current one-way switch. It allows current to flow freely in one direction while severely restricting current flow in the other. A diode is a two-terminal electronic device with low resistance in one direction and high resistance in the other.

Complete answer:
In a PN-junction diode, the potential barrier is the area where the charge must exert extra force to pass. The possible barrier, in other words, is the barrier that prevents the charge carrier from being prevented by the obstructive power.As P and N-type semiconductor materials are combined, a gradient of very high-density charge carriers emerges on both the P and N sides. The N-side free electrons cross the area and begin to combine with the holes, leaving the immobile positive donor ions behind. Similarly, the holes in the P-region combine with the electrons in the N-region, leaving negative acceptor ions behind.

The procedure is repeated until there are enough charge carriers in the P and N regions to oppose the electrons and holes, respectively. Between the N and P-regions, immobile ions (negative acceptor ions and positive donor ions) are localised, forming an electric field that serves as a buffer between charge flows. The region is known as the depletion region because it is formed by reduced ions.

The charge carrier flow is obstructed by the depletion field, which acts as a barrier.Depending on the form of material used, the barrier potential ranges from 0.3 to $0.7\,V$.Germanium Arsenide (GeAs) has a V1.1eV potential barrier. Germanium (Ge) has a potential barrier of 0.3 eV, while Silicon (Si) has a potential barrier of 0.7 eV. As a result, when the diode is zero biassed, Germanium Arsenide has the largest possible barrier.

Hence option C is correct.

Note:Semiconductors are materials that conduct electricity between conductors (usually metals) and nonconductors (insulators) (such as most ceramics). Semiconductors are made up of pure elements like silicon and germanium, as well as derivatives like gallium arsenide and cadmium selenide.