Misalaka Da Faduwar Gunn?

Mai suna Gunn Diode?

Takaitaccen Gunn Diode

Gunn diode shine sasheku mai biyu na doka da yake, wanda ake gina ne da kawai n-doped semiconductor material, ba kawai p-n junction kamar wasu diodes mafi. Gunn diodes zai iya gina su ne da kawai manyan abubuwa, ciki babban mutane, kafin kafin energy valleys a kan conduction band su kamar Gallium Arsenide (GaAs), Indium Phosphide (InP), Gallium Nitride (GaN), Cadmium Telluride (CdTe), Cadmium Sulfide (CdS), Indium Arsenide (InAs), Indium Antimonide (InSb) da Zinc Selenide (ZnSe).

Yadda ake gina shi ya haɗa da koyarwa epitaxial layer a kan degenerate n+ substrate don samun uku n-type semiconductor layers (Figure 1a), inda koyarwanci masu rarrabe su masu kudancin koyarwanci tsakiyar.

A nan ake bayar metal contacts a kowane hagu na Gunn diode don inganta biasing. Circuit symbol ta Gunn diode ya kasance a Figure 1b, wanda yana bambanta da normal diode don nuna rashin ciki p-n junction.

Idan ake bayar DC voltage a Gunn diode, za a faru electric field a kan layers, musamman a tsakiyar active. Daga baya, conduction zai ci gaba a lokacin da electrons ke yi hawa daga valence band zuwa lower valley na conduction band.

V-I plot tana kasance a curve a Region 1 (colored in pink) na Figure 2. Amma, bayan a rasa batun halayi (Vth), conduction current tana ci gaba a Gunn diode kamar yadda ake nuna a curve a Region 2 (colored in blue) na figure.

Wannan shine saboda, a voltages masu kudanci electrons a lower valley na conduction band ke yi hawa zuwa higher valley har zuwa yadda effective mass su yake ci gaba. Reduction a mobility tana ci gaba conductivity, wanda yake ci gaba current wanda ke ji a kan diode.

Saboda haka, diode tana nuna negative resistance region a V-I characteristic curve, daga Peak point zuwa Valley Point. Wannan matsala tana canza transferred electron effect, kuma Gunn diodes suna canza Transferred Electron Devices.

Duk da haka, ya kamata a lura cewa transferred electron effect tana canza Gunn effect, wanda ana kira tun John Battiscombe Gunn (J. B. Gunn) bayan ake gani a shekarar 1963 wanda aka nuna cewa zai iya gina microwaves tare da bayar steady voltage across a chip of n-type GaAs semiconductor. Amma ita ce muhimmanci a lura cewa abu da ake amfani a gina Gunn diodes ya kamata ita ce n-type saboda transferred electron effect tana da shiga electrons kawai holes.

Saboda GaAs shine poor conductor, Gunn diodes ke yi heat masu kudanci kuma ke bukatar heat sink. A microwave frequencies, current pulse tana yi hawa a kan active region, an faru shi a batun voltage. Yawan pulse movement tana ci gaba potential gradient, wanda tana sauran pulse formation.

New current pulse tana iya faru idan pulse na musamman ya samu hagu masu kudancin active region, wanda tana ci gaba potential gradient. Lokacin da pulse tana yi hawa a kan active region tana nuna pulse generation rate da operational frequency ta Gunn diode. Don yawanci oscillation frequency, thickness ta central active region tana bukata.

Duk da haka, nature ta negative resistance tana iya karin Gunn diode tana iya yi aiki a amplifier da oscillator, wanda tana canza Gunn diode oscillator ko Gunn oscaillator.

Muhimman Gunn Diode

• Sun fi a cikin fact wadanda su ne cheap source of microwaves (compared to other options such as klystron tubes)

• Su ne compact in size

• Su yi aiki a large bandwidth and possess high frequency stability.

Matsalolin Gunn Diode

• Su na high turn-on voltage

• Su ne less efficient below 10 GHz

• Su na poor temperature stability.

Ayyuka

• A electronic oscillators don gina microwave frequencies.

• A parametric amplifiers as pump sources.

• A police radars.

• As sensors in door opening systems, trespass detecting systems, pedestrian safety systems, etc.

• As a source for microwave frequencies in automatic door openers, traffic signal controllers, etc.

• A microwave receiver circuits.