Rare-earth doped (Eu3+ or Ce3+) thin layers of tin dioxide (SnO2) are deposited by the sol-gel-dip-coating technique. along with gallium arsenide (GaAs) films. deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices. https://chefesquipmenters.shop/product-category/espresso-machine-parts/