Should Diodes Get Hot?

The power dissipated in a diode depends on the current and voltage. The voltage is about 1 volt for a diode carrying high current. Yours isn't really carrying high current so it shouldn't get very hot. Silicon diodes do get hot if they are carrying high frequency current.

Do diodes generate heat?

Zener diode is heating due to power dissipation. More the power dissipation more the heat, similar to resistor, for example: 2 ohms resistor carrying current of 1A is dissipation 2W of power.

What happens when a diode gets hot?

This application of thermal diode is based on the property of electrical diodes to change voltage across it linearly according to temperature. As the temperature increases, diodes' forward voltage decreases. ... Voltage developed across it varies with the temperature of the diode.