CRYOELECTRONICS – “low temperature electronics”

Have you ever tested keeping your digital wrist watch in the deep freezer of the refrigerator? If not then let me tell you that the watch will stop functioning. Now a question may arise in your mind, Does this mean, people in north and south pole don’t use digital clock?? The answer is “NO”. They do put the digital watch. Now you think, if digital clock doesn’t function in low temperature then how does this happen? (Now you use your brain to find the reason, I’ll say the answer at the end of this blog  )

Now I think you all have got a little about what I am going to explain in my blog.

Do you know what the temperature at the space is? -150°C at the orbit of Jupiter, -230°C at the orbit of Pluto and below -55°C to -65°C at the moon, Mars and other asteroids. In this extreme low temperature, our conventional electronics is of no use. Thus researchers are pioneering a technology called “CRYOELECTRONICS” which is also referred as “Low temperature Electronics”.  Now what is CRYOELECTRONICS then?

Cryoelectronics is made up of the combination of two words. “Cryo” and “Electronics”, among which  ‘Cryo’ is again derived from greek word “kryo” which means ‘icy cold’ or ‘frost’. So simply we can consider cryoelectronics as the low temperature electronics. Generally cryoelectronics deals with the production of low temperature electronic devices. Cryoelectronic materials have high carrier mobility and gives high reliability in low temperature. Their temperature tolerance ranges from -150°C to -273°C. Examples of these devices include complementary metal-oxide semiconductor (CMOS) diodes and field effect transistors (FETs).

Conventional electronics not useful for space, why??

As we now already know that space has extremely low temperature. All the research in spaces can be done only with the help of space ships. Electronics is very essential part of spacecraft as the spacecrafts needs sensors, cameras, wireless data transmitter, control systems. All of these are electronics devices and systems. Thus without electronics the space program is a body without the soul.

Now the point to see is, our traditional electronics which are made up of semiconductors works only between temperatures from -65°C to 125°C. But since our space has temperature more cold than -65°C, In such case our whole electronic system will not function. Thus there is necessity of such technology which can go beyond the extremity of temperature and perform. Thus the concept of Cryoelectronics arose.

One idea could help us to use conventional electronics in space. We can put thermal source for low temperature applications so that the device remains at the normal temperature despite of being of surrounding temperature. But this seems quiet impractical as we need more power to run those thermal sources. This will make electronic devices heavy, bulky and complex too.

How does Cryoelectronics work?

Cryoelectronic materials are generally derived from semiconductors like arsenic, germanium and gallium arsenide, CMOS, high temperature co-fired silicon, amorphous silicon and superconductors. Superconductivity is a state of matter in which the thermal, electric and magnetic properties of many elements, compounds and alloys become drastically changed from its original one when cooled to exceedingly low temperatures. Such elements become superconductor at such low temperature.

Hundreds of materials are known to become superconductors at low temperatures. Aluminium, Tin, Zinc, Lead, Idium, Mercury are few examples of elements which act as superconductors in their crystallographic forms at atmospheric pressure. Not only elements, but alloys and compounds like disilver fluoride or silver subfluoride (Ag2F), compound of carbon and potassium (C8K) and some semiconducting compounds like tin telluride (SnTe) can become superconductors if properly infused with impurities.

Applications

Nowadays cryoelectronics is widely being used in space programs. NASA - The most leading space agency in the world is also using cryoelectronics in development of various devices. NASA is now using semiconductor switching devices, magnetic capacitors, digital to analogue and analogue to digital converters (ADC and DAC)s, operational amplifiers, oscillators, control circuits, power circuits based on cryoelectronics.

Advantages of cryoelectronics are:

1        Increased circuit speed

2        Low power dissipation

3        Fast switching

4        High thermal conductivity

5        Reduction in thermally induced failures

6        Reduced operating power supply

7        Improved digital and analogue circuit performance (based upon noise margin, switching and gain band-width)

Due to these advantages cryoelectronics is nowadays applied in outer space satellites, cosmic radiation detectors, UV (ultraviolet) and IR (Infrared) ray detectors, medical instruments, high speed circuits, dynamic Random Access Memories (RAMs) and organic electronics.

Nowadays many people are involved in more improvement and further research on cryoelectronics. You can also choose your career in the field of cryoelectronics. Best of Luck.

If you like the post, please share to your friends and please comment so that I can detect my good points, else too please comment so that I will know my faults.

(Answer Of question asked in the first paragraph:

It is explained in Why conventional electronics will not work’s last paragraph. The watch is always put on wrist. No matter whatever the outer temperature is, your body temperature normally remains at 37°C i.e. 98°F, thus our body will act as thermal source for the watch and keep it in normal temperature. Thus the watch works.)

Reference:

Adkoli, V.R.  “Low temperature Electronics for space.” EFY.2012

©Bishal Bhandari