79 views

Red (R), Green(G) and Blue (B) Light Emitting Diodes (LEDs) were fabricated using $\text{p-n}$ junctions of three different inorganic semiconductors having different band-gaps. The built-in voltages of red,green and blue diodes are $V_{R}$, $V_{G}$ and $V_{B},$respectively. Assume donor and acceptor doping to be the same ($N_{A}$ and $N_{D},$ respectively) in the $\text{p}$ and $\text{n}$ sides of all three diodes. Which one of the following relationships about the built-in voltages is TRUE?

1. $V_{R}>V_{G}>V_{B}$
2. $V_{R}<V_{G}<V_{B}$
3. $V_{R}=V_{G}=V_{B}$
4. $V_{R}>V_{G}<V_{B}$