Cryogenic electronics based upon semiconductive devices, superconductive devices, or a combination of the two present opportunities for a wide variety of novel, fast, and low power devices. However, such cryogenic electronics require cooling which is typically achieved through fluid refrigerants such as liquid nitrogen or liquid helium. Solid state refrigeration based upon adiabatic demagnetization in paramagnetic salts offers one alternative but requires that the solid state cooler and cryogenic electronic circuits be different physical elements. The inventors present solid state cooling for semiconductor materials including but not limited to silicon. Beneficially active electronic devices can be integrated monolithically with solid state semiconductor coolers exhibiting magnetic cooling within the whole substrate or predetermined regions of the substrate. Alternatively, active devices may be formed with semiconductor layers integral to them that exhibit magnetic cooling.