The barrier potential across an unbiased silicon pn junction is about

Explanation

Silicon has a barrier of roughly 0.7 V, while germanium's is about 0.3 V, which is why a silicon diode needs about 0.7 V across it before it conducts appreciably. This forward voltage drop must be allowed for in circuit calculations. Silicon is preferred for most applications because it tolerates higher temperatures and has lower leakage.