GATE EC 2003 Set 1 Q40 — Electronic Devices

Match items in Group $1$ with items in Group $2,$ most suitably.

$$\begin{array}{ll} \textbf{Group 1} & \textbf{Group 2} \\ \text{P LED} & \text{1 Heavy doping} \\ \text{Q Avalanche photodiode} & \text{2 Coherent radiation} \\ \text{R Tunnel diode} & \text{3 Spontaneous emission} \\ \text{S LASER} & \text{Current gain} \end{array}$$