New routes to metal‐organic precursors; growth of high purity AIGaAs by CBE using a novel amine adduct of triisopropylgallium

Abstract

MATERIALSthe similar nitronyl nitroxide radicals NITPh and The interactions between these two spin densities of opposite sign can therefore be considered to give rise to the required ferromagnetic inter-plane couplings.In conclusion we have presented evidence of a ferromagnetic transition in the nitronyl nitroxide NIT(SMe)Ph. The diffuse electronic cloud of the sulfur atom in the radical substituent generates sufficiently strong ferromagnetic interactions even at large distances. It may be hoped that on finding radicals with more favorable packing higher critical temperature can be achieved. ( VCH Verlug.gewllschuft mhH, 0-69469 Wrmham, 1995 O935-9648/95/O505-O4XO $ 5 00+ 2510 Adv Mawr 1995 7, No 5

Synthesis of ultra-high purity trialkylgallium MOVPE precursors. Crystal structures of triethylgallium and triisopropylgallium adducts with macrocyclic tertiary amines

“…7 It has been shown that traces of diethyl ether, Et 2 O, in the group III trialkyl precursor is a major source of oxygen contamination in AlGaAs and AlInAs layers grown by MOVPE or chemical beam epitaxy (CBE). 8,9 The trace Et 2 O originates from the organometallic synthesis reaction, which usually involves the alkylation of a metal trihalide (MX 3 ) by a Grignard reagent (RMgX), or an alkyllithium compound (RLi). 10 The Et 2 O subsequently forms an adduct with the R 3 Ga or R 3 In precursor and is dif®cult to displace completely using conventional adduct puri®cation techniques.…”

“…It has been shown that Grignard reagents can be synthesised in trialkylamine solvents, 11 and we have thus developed a proprietary synthetic route to R 3 M compounds (R~Ga, In) in which the ether solvent is replaced by trialkylamines such as NEt 3 and NMe 2 Et. 8,12 This leads to adducts such as Pr i 3 Ga(NEt 3 ), from which AlGaAs with signi®cantly reduced oxygen contamination has been grown by CBE. 8,12 However, these adducts have low vapour pressures (v1 Torr at 35 ³C) which limits their widespread application in CBE or MOVPE.…”

“…8,12 This leads to adducts such as Pr i 3 Ga(NEt 3 ), from which AlGaAs with signi®cantly reduced oxygen contamination has been grown by CBE. 8,12 However, these adducts have low vapour pressures (v1 Torr at 35 ³C) which limits their widespread application in CBE or MOVPE. In a preliminary communication, 13 we described how NEt 3 can be readily displaced from Pr i 3 Ga(NEt 3 ) and Et 3 Ga(NEt 3 ) by the addition of 4,4'-methylenebis(N,N'dimethylaniline) (MBDA) or the multidentate aza-crown ligands 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (N 4 -aza crown) and 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16hexaazacyclooctadecane (N 6 -aza crown).…”

Next generation adduct purification techniques for low oxygen content metal alkyls

“…2 The low oxygen content of the AlGaAs layers resulting from the Pr i 3 Ga/AlH 3 (NMe 2 Et) precursor combination gave rise to films with good photoluminescence properties. SIMS analysis of a 1 µm thick undoped Al 0.3 Ga 0.7 As showed that oxygen levels were at or below the SIMS detection limit of 1 × 10 17 cm -3 , which is comparable to the best results obtained on the same reactor using Et 3 Ga or the Pr i 3 Ga(NEt 3 ) 0.6 adduct.…”

“…Therefore, for the production of low oxygen content metal alkyls in general it is necessary to entirely eliminate Et 2 O from the synthesis route. 2,9 However, these adducts have low vapor pressures (< 1 torr at 35°C) which limits their widespread application in CBE or MOVPE. In addition, commercially available R 3 Al reagents are generally of uncertain purity, containing high levels of organic and metallic impurities, so that routes involving RMgX or RLi alkylating agents are preferred for large scale manufacture of high purity R 3 Ga or R 3 In MOCVD precursors.…”