- Semiconductor devices must face various space environments ranging from extremely low temperatures in the upper atmosphere to very high temperatures in power systems, and from low levels of ionizing radiation to high levels of neutron irradiation. Pressure varies from atmospheric pressure near the ground to vacuum at high altitudes. The semiconductor materials and devices are affected by the following external mechanisms: temperature, optical radiation, impurities and ionized gases, nuclear radiation, particle bombardment and pressure. This paper will discuss the effects of (gamma) -irradiation and pressure on optoelectronic devices such as related photodiodes, light-emitting diodes, and charge-coupled devices. These effects will be related not only to bulk effects, but also to surface effects.