Notebook

Tantalum CVD Precursors

Halide Precursors

Tantalum Pentafluoride TaF5

  • Melting point 96°C
  • Boiling point 229.2°C
  • Condensed phase density  4.98 g/cm3 (at 15°C),  3.88 g/cm3 (at melting point)
  • Molar mass   275.9 g/mol
Saturated vapor pressure over liquid TaF5
Saturated vapor pressure over liquid TaF5

Tantalum Pentachloride TaCl5

  • Melting point 216.5°C
  • Boiling point 236°C
  • Condensed phase density 3.68  g/cm3 (at 28°C), 2.68  g/cm3 (at melting point)
  • Molar mass  358.2  g/mol
Saturated vapor pressure over TaCl5
Saturated vapor pressure over TaCl5

Fairbrother, F., Grundy, K. H., & Thompson, A. (1965). 121. The halides of niobium and tantalum. Part VIII. The densities, viscosities, and self-ionisation of niobium and tantalum pentafluorides. Journal of the Chemical Society (Resumed), 761-765.

Fairbrother, F., & Frith, W. C. (1951). 675. The halides of niobium (columbium) and tantalum. Part III. The vapour pressures of niobium (columbium) and tantalum pentafluorides. Journal of the Chemical Society (Resumed), 3051-3056.

Alexander, K. M., & Fairbrother, F. (1949). S 48. The halides of columbium (niobium) and tantalum. Part I. The vapour pressures of columbium (niobium) and tantalum pentachlorides and pentabromides. Journal of the Chemical Society (Resumed), S223-S227.

Niobium CVD Precursors

Halide precursors

Niobium Fluoride NbF5

  • Melting point 78.9°C
  • Boiling point 233.3°C
  • Condensed phase density 3.29g/cm3 (at 25°C), 2.69g/cm3 (at melting point)
  • Molar mass   187.9g/mol
Saturated vapor pressure over solid NbF5
Saturated vapor pressure over solid NbF5
Saturated vapor pressure over liquid NbF5
Saturated vapor pressure over liquid NbF5

Niobium Chloride NbCl5

  • Melting point 205°C
  • Boiling point 247.5°C
  • Condensed phase density 2.75 g/cm3 (at 25°C), 2.07 g/cm3 (at melting point)
  • Molar mass  270.2 g/mol
Saturated vapor pressure over NbCl5
Saturated vapor pressure over NbCl5

Fairbrother, F., & Frith, W. C. (1951). 675. The halides of niobium (columbium) and tantalum. Part III. The vapour pressures of niobium (columbium) and tantalum pentafluorides. Journal of the Chemical Society (Resumed), 3051-3056.

Junkins, J. H., Farrar Jr, R. L., Barber, E. J., & Bernhardt, H. A. (1952). Preparation and Physical Properties of Niobium Pentafluoride1. Journal of the American Chemical Society, 74(14), 3464-3466.

Fairbrother, F., Grundy, K. H., & Thompson, A. (1965). 121. The halides of niobium and tantalum. Part VIII. The densities, viscosities, and self-ionisation of niobium and tantalum pentafluorides. Journal of the Chemical Society (Resumed), 761-765.

Alexander, K. M., & Fairbrother, F. (1949). Vapor Pressures of TaCl5, TaBr5, TaI5, NbCl5, NbBrs. J. Chem. Soc, 2472, 223.

Alexander, K. M., & Fairbrother, F. (1949). S 48. The halides of columbium (niobium) and tantalum. Part I. The vapour pressures of columbium (niobium) and tantalum pentachlorides and pentabromides. Journal of the Chemical Society (Resumed), S223-S227.

Molybdenum CVD Precursors

Halide precursors (HVPE)

Molybdenum Chloride MoCl5

  • Melting point 194°C
  • Boiling point 268°C
  • Condensed phase density 2.925g/cm3 (at 25°C)
  • Molar mass  273.2 g/mol
MoCl5 saturated vapor pressure
MoCl5 saturated vapor pressure

Molybdenum Fluoride MoF6

  • Melting point 17.5°C
  • Boiling point 35°C
  • Condensed phase density 2.551g/cm3 (at 25°C)
  • Molar mass  209.9 g/mol
MoF6 saturated vapor pressure
MoF6 saturated vapor pressure

Shchukarev, S. A.; Suvorov, A. V. (Vestn. Leningr. Univ. Fiz. Khim. 16 No. 1 [1961]87/99, 89; C.A. 1961 16117)

Ruff, O., & Ascher, E. (1929). Fluorides of the eighth group of the periodic system. Z. Anorg. Allgem. Chem, 183, 193-213.

Cady, G. H., & Hargreaves, G. B. (1961). 305. The vapour pressures of some heavy transition-metal hexafluorides. Journal of the Chemical Society (Resumed), 1563-1568.

Tungsten CVD Precursors

Halide precursors (HVPE)

Tungsten Hexachloride WCl6

  • Melting point 281.5°C
  • Boiling point 348°C
  • Condensed phase density 3.52g/cm3 (at 25°C)
  • Molar mass 396.57 g/mol
WCl6 saturated vapor pressure
Saturated vapor pressure of Tungsten Hexachloride (WCl6)

Tungsten Hexafluoride WF6

  • Melting point 2.5°C
  • Boiling point 17.3°C
  • Condensed phase density 4.56 g/cm3 (solid T<-8.5°C), 3.99 g/cm3 (solid at 0°C), 3.4 g/cm3 (liquid at 20°C)
  • Molar mass 297.84 g/mol

 

Stevenson, F. D., Wicks, C. E., & Block, F. E. (1963). Vapor pressure of tungsten (VI) chloride and hafnium (IV) iodide by a metal diaphragm technique (No. BM-RI-6367). Bureau of Mines, Albany, OR (USA). Albany Metallurgy Research Center.

Siegel, S., & Northrop, D. A. (1966). X-ray diffraction studies of some transition metal hexafluorides. Inorganic Chemistry, 5(12), 2187-2188

Alyea, E. D., Gallagher, L. B., Mullens, J. H., & Teem, J. M. (1957). A WF6 bubble chamber. Il Nuovo Cimento (1955-1965), 6(6), 1480-1488.

 

Zirconium CVD Precursors

Halide precursors (HVPE)

Zirconium Tetrachloride ZrCl4

  • Melting point 437°C (21.8 atm)
  • Sublimation temperature 315°C (1 atm)
  • Condensed phase density  2.8g/cm3 (at 25°C)
  • Molar mass  233.04g/mol
ZrCl4 saturated vapor pressure
Zirconium Tetrachloride saturated vapor pressure

References

Tangri, R. P., and D. K. Bose. “Vapour pressure measurement of zirconium chloride and hafnium chloride by the transpiration technique.” Thermochimica acta 244 (1994): 249-256.

Hafnium CVD Precursors

Halide precursors (HVPE)

Hafnium Tetrachloride HfCl4

  • Melting point 432°C (vapor pressure 44.4 atm)
  • Sublimation temperature 315°C (1 atm)
  • Condensed phase density  3.86 g/cm3 (at 25°C)
  • Molar mass  320.3 g/mol
HfCl4 saturated vapor pressure
Hafnium Tetrachlodire saturated vapor pressure

References

Tangri, R. P., and D. K. Bose. “Vapour pressure measurement of zirconium chloride and hafnium chloride by the transpiration technique.” Thermochimica acta 244 (1994): 249-256.

Gallium CVD precursors

Halide precursors (HVPE)

Gallium Trichloride GaCl3

  • Melting point 78°C
  • Boiling point 201°C
  • Condensed phase density 2.47g/cm3 (at 25°C)
  • Molar mass  176.08 g/mol
GaCl3 saturated vapor pressure
Saturated vapor pressure of Gallium Trichloride (GaCl3)

Gallium Tribromide GaBr3

  • Melting point 122°C
  • Boiling point 279°C
  • Condensed phase density  3.69g/cm3 (at 25°C)
  • Molar mass  309.4g/mol

Gallium Triiodide GaI3

  • Melting point  210°C
  • Boiling point  346°C
  • Condensed phase density  4.15g/cm3 (at 25°C)
  • Molar mass   450.4g/mol

Metallic gallium chlorination

Gallium chlorides can be produced inside a reactor, by passing dry hydrogen chloride (HCl) or Chlorine (Cl2) gas over a boat with liquid gallium. The composition of produced chlorides mainly depends on chlorination temperature – at temperatures below ~350°C Gallium trichloride GaCl3 and it’s dimer Ga2Cl6 are main reaction products. At higher temperatures gallium monochloride GaCl becomes dominant.

Ga chlorination vapor composition
Main products of gallium chlorination with Hydrogen Chloride (HCl)

Aluminum CVD precursors

Halide precursors (HVPE)

Aluminum Trichloride AlCl3

  • Melting point 192.6°C
  • Boiling point 182.7°C (sublimes)
  • Condensed phase density 2.44 g/cm3 (at 25°C)
  • Molar mass 133.34 g/mol
AlCl3 saturated vapor pressure
Saturated vapor pressure ofAlCl3

Aluminum Tribromide AlBr3

  • Melting point 98°C
  • Boiling point 255°C
  • Condensed phase density 3.01 g/cm3 (at 25°C)
  • Molar mass 266.69 g/mol

Aluminum Triiodide AlI3

  • Melting point  191°C
  • Boiling point 382°C
  • Condensed phase density 3.98g/cm3 (at 25°C)
  • Molar mass 407.69 g/mol

Metallic aluminum chlorination

Aluminum chlorides can be produced inside a reactor, by passing dry hydrogen chloride (HCl) or Chlorine (Cl2) gas over a boat with aluminum pellets. The composition of produced chlorides mainly depends on chlorination temperature – at temperatures below 900°C aluminum trichloride AlCl3 and it’s dimer Al2Cl6 are main reaction products. At higher temperatures aluminum monochloride AlCl becomes dominant.

Aluminum chlorination products
Main products of aluminum chlorination with Hydrogen Chlodire (HCl)

 

Thermal management of high power HB LED

The efficiency of transformation of electricity into the light is a key point for HB LEDs. Efficiency of the typical LEDs achieves 40% to 50%. That means that more than 50% of the electrical power transforms into heat. The reason is a numerous of non-radiative recombination channels in the LEDs, because of high density of dislocations and point defects, and light extraction losses.

The strategic fight for LED high efficiency is the fight for high quality of the material and, in particular, for low dislocation density. Therefore, GaN or AlN substrates should be used to get high efficient HB LEDs or low threshold LDs.

However, the shortest way to get HB LEDs today is to increase electrical power applied to the LEDs and to improve LEDs thermal management at the same time.

Continue reading Thermal management of high power HB LED