Trimethylindium

Trimethylindium
Preferred IUPAC name

Trimethylindium
Systematic name

Trimethylindigane[1]
Identifiers
CAS number 3385-78-2 Y
PubChem 76919
ChemSpider 69370 Y
EC number 222-200-9
Jmol-3D images Image 1
Properties
Molecular formula InC3H9
Molar mass 159.922 g mol-1
Exact mass 159.974303616 g mol-1
Appearance White, opaque crystals
Density 1.568 g cm-3 (at 20 °C)
Melting point

88 °C, 361 K, 190 °F
Boiling point

134 °C, 407 K, 273 °F (decomposes above 101 °C)
Solubility in water Reacts
Thermochemistry
Std enthalpy of
formation ΔfHo298		 150.5-169.7 kJ mol-1
Hazards
Main hazards Pyrophoric
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Trimethylindium (abbr: TMI or TMIn), In(CH3)3, (CAS #: 3385-78-2) is the preferred metalorganic source of Indium for metalorganic vapour phase epitaxy (MOVPE) of indium-containing compound semiconductors, such as InP, InAs, InN, InSb, GaInAs, InGaN, AlGaInP, AlInP, AlInGaNP etc. TMI is a white, crystalline and sublimable solid, with melting point 88 °C. TMI is known to be pyrophoric, i.e. it ignites sponteneously upon contact with air; and its decomposition is often found to be uncontrollable as the temperature of its surrounding exceeds its melting point (i.e. > 88°C) and reaches 101 °C and above. TMI is also reported to exhibit autocatalytic behavior during its thermal decomposition.[2] Hence TMI needs to be handled with utmost care and caution, e.g. stored in preferably cool, dry place at 0-25°C, and operating temperatures not to exceed 50 °C to avoid deterioration. TMI is also known to react extremely violently with oxidizers and polyhalogenated compounds (such as CCl4 or CBrCl3) with which TMI is known to be incompatible. Hence the situations involving admixtures of TMI with oxidizers and polyhalogenated compounds must be avoided as potentially dangerous and explosive.

Contents

Semiconductor grade TMI

The advancements in synthesis and purification chemistries have now made it possible to attain highest purity in TMI (99.9999% pure or greater), which is imperative for improved performance of semiconductor applications. Recent reports indicate some of the best electrical properties for InP alloys so far, by MOVPE using highest purity TMI available today, e.g. electron mobilities (Hall data) as high as 287,000 cm²/Vs at 77 K and 5400 cm²/Vs at 300 K, and background carrier concentration as low as 6×1013 cm−3 [3] [4], which were not practically achievable in the past.

Accurate vapor pressure equation for TMI

The vapor pressure equations reported in the literature for TMI have been found to offer overestimated vapor pressure of TMI, often by as much as 20–40%. Not knowing the accurate vapor pressure has thus been a concern to crystal growers. In a recent study [5], it was expermentally confirmed that the vapor pressure equation, log P (Torr)=10.98–3204/T (K), provides the most accurate vapor pressures of TMI within a wide range of MOVPE growth conditions.

References

  1. ^ "Trimethylindium - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information. 27 March 2005. Descriptors Computed from Structure. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=76919&loc=ec_rcs. Retrieved 21 September 2011. 
  2. ^ Chemistry of Materials (2000); doi:10.1021/cm990497f
  3. ^ Journal of Crystal Growth (2002); doi:10.1016/S0022-0248(02)01854-7
  4. ^ Journal of Crystal Growth (2004); doi:10.1016/j.jcrysgro.2004.09.006
  5. ^ Journal of Crystal Growth (2008); doi:10.1016/j.jcrysgro.2007.11.196

External links