No, a pn junction without metal electrodes around it would not conduct radio waves in the same way as an antenna or a metal conductor would. A pn junction, which is the basic building block of semiconductor devices like diodes and transistors, is designed to control the flow of electric current under certain conditions.
While a pn junction can interact with electromagnetic waves, including radio waves, it does not function as a dedicated antenna for transmitting or receiving those waves. The behavior of a pn junction with respect to electromagnetic waves depends on factors such as the frequency of the waves, the properties of the semiconductor material, and the configuration of the junction.
At radio wave frequencies, the behavior of a pn junction without metal electrodes would not result in efficient transmission or reception of radio waves. The absence of metal electrodes means that there are no structures specifically designed to efficiently couple with the electromagnetic fields associated with radio waves.
To effectively transmit or receive radio waves, it is necessary to use dedicated antennas that are designed to resonate at specific frequencies and efficiently couple with the electromagnetic fields. These antennas are typically constructed using metal conductors or arrays of conductive elements.
In summary, while a pn junction can interact with electromagnetic waves, it does not act as a dedicated antenna for transmitting or receiving radio waves without the presence of metal electrodes or other specifically designed structures.