- •Task №1
- •3. Evaluation of the tangential sensitivity of the detector diode
- •4. The main similarities and differences in the functional role, structure, and parameters of microwave devices numbered 1 (detector diode) and 2 (pin diode)
- •4.1 Detector diode
- •4.1.1 The functional role of the detector diode
- •4.1.2 Structure of the detector diode
- •4.1.3 Parameters of the detector diode
- •1. Volt-ampere characteristic:
- •2. Total resistance:
- •3. Cutoff frequency:
- •4. Current sensitivity:
- •5. Tangential sensitivity:
- •6. Noise ratio:
- •4.2 Pin diode
- •4.2.1 The functional role of the pin diode
- •4.2.2 Pin diode structure
- •4.2.3 Pin diode parameters
- •1. Volt-ampere characteristic:
- •2. Transmission and locking losses:
- •3. Quality coefficient:
- •4. Turn-on time of the pin diode:
- •5. Cutoff frequency:
- •4.3 Similarities and differences of the detector diode and pin diode
- •4.3.1 Differences between the detector diode and pin diode
- •4.3.2 Similarities of the detector diode and pin diode
- •5. Description of circuit models of microwave diodes with positive dynamic resistance
- •5.1 Description of the pin diode circuit model
- •5.2 Description of the mixer diode circuit model
- •Task №2 Diodes with negative dynamic resistance.
- •1.2 Gunn diode graphs (GaAs)
- •2. Representation of the device in the form of a layered structure with different differential mobility
- •2.1 Representation of the impatt diode in the form of a layered structure with different differential mobility
- •2.2 Representation of the Gunn diode in the form of a layered structure with different differential mobility
- •Task №3 Transistors.
- •1.2 Calculation of the gate length of a field-effect transistor
- •1.3 Analysis of the obtained results of calculating the thickness of the bipolar transistor base and the gate length of the field effect transistor
- •1.4 Calculation of the angle of flight of a bipolar transistor
- •1.5 Calculation of the angle of flight of a field-effect transistor
- •2.1 Advantages and disadvantages of hemt (High Electron Mobility Transistor)
- •2.2 Advantages and disadvantages of transistors with ballistic transport
- •2.3 Calculation of the thickness of the high-alloyed hemt region
- •3.1 GaN usage trend
- •3.2 InP usage trend
- •3.3 SiC usage trend
- •3.4 Diamond (c) usage trend
- •4.1 Input and output volt-ampere characteristics of three sbgfet with the same size, doping level, but made of Si, GaN, GaAs
- •4.2 How will the characteristics change if the gate width is increased
- •6. Connection of low-frequency noise with transistor manufacturing technology
- •7. Image of a low-signal equivalent Schottky-barrier transistor circuit. Explanation of how such a scheme is better or worse than s-parameters
3.3 SiC usage trend
Silicon carbide (SiC) is used for several reasons, namely [34]:
1. Firstly, the band gap is large compared to Si and GaAs – about 3,3 eV, which means a larger operating temperature range (theoretically up to ~ 1000°C), as well as the possibility of creating devices emitting in the entire visible light range.
2. Secondly, due to an order of magnitude greater value of the SiC breakdown field, compared with silicon, at the same value of the breakdown voltage, the doping level of the SiC diode can be two orders of magnitude higher than that of silicon. And consequently, its sequential resistance will be less and, as a result, the specific power will be greater. This is also the reason for the high radiation resistance of SiC devices.
3. Thirdly, high thermal conductivity (for polycrystalline SiC – at the level of thermal conductivity of copper), which simplifies the problem of heat dissipation. This property in combination with high permissible operating temperatures and high saturation rates of carriers (high saturation currents of field-effect transistors) makes SiC devices very promising for use in power electronics.
4. Fourth, the high Debye temperature, which determines the temperature at which elastic vibrations of the crystal lattice (phonons) occur with the maximum frequency for a given material. The Debye temperature can be considered as a parameter characterizing the thermal stability of a semiconductor. If this temperature is exceeded, fluctuations can become inelastic and lead to the destruction of the material.
5. Fifth, the presence of its own (that is, made of the same material as the semiconductor structure) substrate of a large size. That, as well as the possibility of obtaining SiC n- and p-types of conductivity and the presence of its own oxide (SiO2), make it possible to manufacture any types of semiconductor devices based on SiC.
Also, the higher thermal conductivity of SiC (4,9 W/m K) compared to the thermal conductivity of GaN (1,5 W/cm K) or Si (1,5 W/m K) means that devices based on SiC are superior to devices based on GaN or Si in thermal conductivity and theoretically can work at a higher specific power. Higher thermal conductivity, together with a wide band gap and a high critical breakdown field strength, gives SiC semiconductors an advantage in cases where the key required characteristic of the device is high power.
SiC-based field-effect transistors reveal new applications at higher power and voltage. As a direct replacement for IGBT transistors and silicon MOSFET transistors, silicon carbide field effect transistors demonstrate low-loss operation at high temperatures, low resistance in the open state over the entire temperature range and low switching losses. MOSFET transistors made of SiC, having higher breakdown voltages, better cooling performance and temperature resistance, due to their characteristics can be made physically compact. IGBT transistors (bipolar transistors with an isolated gate) are used primarily at switching voltages above 600 V, but SiC-based materials allow the use of MOSFET transistors at voltages up to 1700 V and higher currents. Also, MOSFET transistors based on SiC have significantly lower switching losses compared to IGBT transistors and operate at relatively higher frequencies [30].