Final answer:
The statement that 'Their semiconductor properties change as materials age' is NOT a characteristic of semiconductors. While individual devices may degrade over time, aging is not a fundamental property of semiconductor materials. Doping is used to enhance semiconductor properties, which is crucial in electronics.
Step-by-step explanation:
To answer the question of which of the following is NOT a characteristic of semiconductors: They are better conductors than insulators, they can be contaminated to improve their semiconductor properties, they are abundantly found in nature, their semiconductor properties change as materials age, or all of the above; we need to look at the properties of semiconductors.
A key feature of semiconductors is their intermediate resistivity, which is less than that of insulators but more than that of conductors. Semiconductors also have free charge densities that are lower than those in conductors but higher than in insulators. This property makes semiconductors very useful in modern electronics. Moreover, the addition of impurities, a process known as doping, can significantly alter their conductivity.
The characteristic that is NOT true about semiconductors is that 'Their semiconductor properties change as materials age' as a general characteristic.
While certain semiconductor characteristics can change over time due to factors like defects or damage from radiation, the phrase as stated might imply that aging itself changes the semiconductor properties, which is not an inherent characteristic of semiconductors.
It's also worth clarifying that 'they can be contaminated to improve their semiconductor properties' refers to the intentional introduction of impurities in a controlled manner (doping) to create p-type or n-type semiconductors, which is essential in creating electronic devices.