Telluroether and Selenoether Complexes as Single Source Reagents for Low Pressure Chemical Vapor Deposition of Crystalline Ga₂Te₃ and Ga₂Se₃ Thin Films

Abstract

The neutral complexes [GaCl 3 (E n Bu 2 )] (E = Se or Te), [(GaCl 3 ) 2 { n BuE(CH 2 ) n E n Bu}] (E = Se, n = 2; E = Te, n = 3), and [(GaCl 3 ) 2 { t BuTe(CH 2 ) 3 Te t Bu}] are conveniently prepared by reaction of GaCl 3 with the neutral E n Bu 2 in a 1:1 ratio or with n BuE(CH 2 ) n E n Bu or t BuTe(CH 2 ) 3 Te t Bu in a 2:1 ratio and characterized by IR/Raman and multinuclear ( 1 H, 71 Ga, 77 Se-{ 1 H}, and 125 Te{ 1 H}) NMR spectroscopy, respectively, all of which indicate distorted tetrahedral coordination at Ga. The tribromide analog, [GaBr 3 (Se n Bu 2 )], was prepared and characterized similarly. A crystal structure determination on [(GaCl 3 ) 2 { t BuTe(CH 2 ) 3 Te t Bu}] confirms this geometry with each pyramidal GaCl 3 fragment coordinated to one Te donor atom of the bridging ditelluroether, Ga−Te = 2.6356(13) and 2.6378(14) Å. The n Bu-substituted ligand complexes serve as convenient and very useful single source precursors for low pressure chemical vapor deposition (LPCVD) of single phase gallium telluride and gallium selenide, Ga 2 E 3 , films onto SiO 2 and TiN substrates. The composition and morphology were confirmed by SEM, EDX, and Raman spectroscopy, while XRD shows the films are crystalline, consistent with cubic Ga 2 Te 3 (F4̅ 3m) and monoclinic Ga 2 Se 3 (Cc), respectively. Hall measurements on films grown on SiO 2 show the Ga 2 Te 3 is a p-type semiconductor with a resistivity of 195 ± 10 Ω cm and a carrier density of 5 × 10 15 cm −3 , indicative of a close to stoichiometric compound. The Ga 2 Se 3 is also p-type with a resistivity of (9 ± 1) × 10 3 Ω cm, a carrier density of 2 × 10 13 cm −3 , and a mobility of 20−80 cm 2 / V·s. Competitive deposition of Ga 2 Te 3 onto a photolithographically patterned SiO 2 /TiN substrate indicates that film growth onto the conducting and more hydrophobic TiN is preferred.

Solution based CVD of main group materials

“…68 They also have a potential application as passivating layers for III-V devices and are related to ternary phases, such as CuInE 2 (E = S or Se) with uses in solar cells. 73,74 Examples of precursors to metal chalcogenides have been reviewed. The wurtzite-type hexagonal structures, a-Ga 2 S 3 and b-Ga 2 S 3 , as well as a monoclinic g-Ga 2 S 3 phase exists.…”

Synthesis, Structure and Application of Intramolecularly‐Coordinated Gallium Chalcogenides: Suitable Single‐Source precursors for GaxSey Materials

“…The resulting material contained phosphorus content at 15–20 % according to energy‐dispersive X‐ray spectroscopy (EDX) . In 2013, Reid and co‐workers prepared telluroether and selenoether complexes of GaCl 3 and used them as SSPs for low pressure CVD of single phase Ga 2 E 3 . In contrast, the deposition of amorphous GaSe layers was reported infrequently .…”

A comparative ab initio study to investigate the rich structural variety and electronic properties of GamTen (m = 1, 2 and n = 1–4) with analogous oxides, sulfides and selenides

“…The Ga-Te bond lengths of the neutral gallium tellurides are within the range 2.357-2.845 Å Ga-Te bond lengths of the gallium tellurides are in agreement with mixed chalcogenide cubanes[40], KGa 2 Te 6[41], monoclinic GaTe[42,43], hexagonal GaTe[44], Ga 2 Te 5[45] and telluroether gallium complexes[9]. The Te-Te bond lengths of the neutral gallium tellurides are MP2).…”