Re: low power design
You can't make a silicon transistor work with a 0.5 Volt supply.
The semiconductor properties of silicon dictate a theoretical minimum of 0.7V on the reverse-biased junction. So the practical lower limit on power supply voltage is about 0.9V [ you still need some voltage drop over and above the 0.7V. You can't get much lower than that.
Added after 2 minutes:
...And another thing:
You mentioned low power in your subject line. It is true that for decades designers have been able to lower the power consumption of their chips by migrating to steadily lower voltages. But we have reached the minimum possible supply voltage now, and that is why there is so much interest in other power savings techniques like clock gating and power gating.