Films of hydrogenated amorphous GaAs have been deposited by reactive sputtering. Substrate temperatures varied in the range 20-200-degrees-C, while hydrogen pressure varied between 2.7 x 10(-2) and 45 x 10(-2) Pa. The deposition rate ranged between 0.24 and 0.87 angstrom s-1 and the film thickness between 0.34 and 0.78 mum. Substrate temperature or hydrogen pressure were allowed to change, in different depositions, to obtain groups of samples deposited with only one variable parameter. TEM and THEED measurements were made to study the films. The main results are that variations in the substrate temperature or argon pressure affect the deposition rate. A more complicated situation is found for the variation of hydrogen pressure. For hydrogen content in gas phase lower than 10%, the mean diameters of the agglomerates decrease and the deposition rate increases. These two effects can be explained by the role of hydrogen on the deposition process, according to its major or minor content in the plasma phase. With a low hydrogen content the morphology tends to be regular. The pressure of the sputtering argon gas controls the morphology, while the addition of hydrogen influences the short-range order when the argon pressure is relatively low.
Structural characterization of hydrogenated amorphous GaAs.
MURRI, Roberto Vittorio;PINTO, Nicola;
1992-01-01
Abstract
Films of hydrogenated amorphous GaAs have been deposited by reactive sputtering. Substrate temperatures varied in the range 20-200-degrees-C, while hydrogen pressure varied between 2.7 x 10(-2) and 45 x 10(-2) Pa. The deposition rate ranged between 0.24 and 0.87 angstrom s-1 and the film thickness between 0.34 and 0.78 mum. Substrate temperature or hydrogen pressure were allowed to change, in different depositions, to obtain groups of samples deposited with only one variable parameter. TEM and THEED measurements were made to study the films. The main results are that variations in the substrate temperature or argon pressure affect the deposition rate. A more complicated situation is found for the variation of hydrogen pressure. For hydrogen content in gas phase lower than 10%, the mean diameters of the agglomerates decrease and the deposition rate increases. These two effects can be explained by the role of hydrogen on the deposition process, according to its major or minor content in the plasma phase. With a low hydrogen content the morphology tends to be regular. The pressure of the sputtering argon gas controls the morphology, while the addition of hydrogen influences the short-range order when the argon pressure is relatively low.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
