PHOTOLUMINESCENCE AS A PROBE OF THE ADSORPTION OF GASEOUS BORANES ONTO THE SURFACE OF CADMIUM SELENIDE CRYSTALS

被引:23
作者
NEU, DR [1 ]
OLSON, JA [1 ]
ELLIS, AB [1 ]
机构
[1] UNIV WISCONSIN,DEPT CHEM,MADISON,WI 53706
关键词
D O I
10.1021/j100123a041
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Gas-phase adsorption of several boranes (BF3, MeBBr2, Me2BBr, and Et3B) onto the surface of etched, single-crystal n-CdSe quenches the band gap photoluminescence (PL) relative to its intensity in vacuum (pressure approximately 10(-5) Torr). The PL quenching is consistent with the Lewis acidic nature of the boranes and is dependent on substituents: PL quenching follows the order BF3 > MeBBr2 > Me2BBr > Et3B. The magnitude of the PL quenching can be fit to a dead-layer model, permitting an estimate of the adduct-induced expansion of the depletion width in the semiconductor resulting from exposure to these Lewis acids; dead-layer expansions as large as approximately 600 angstrom have been measured. The borane-induced PL changes are pressure-dependent and, for all but BF3, can be fit by a simple Langmuir adsorption isotherm model, yielding equilibrium constants for adduct formation, K(P), that range from on the order of 10 atm-1 for Me2BBr and Et3B to 10(3) atm-1 for MeBBr2. Detection limits can reach values of as low as approximately 0.001 Torr for BF3. The use of these effects as the basis for on-line sensors in chemical vapor deposition (CVD) processes is discussed.
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页码:5713 / 5716
页数:4
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