Engineering topics

Lien, C.-D.

Publications and source records attributed to Lien, C.-D..

4 records

NASA NTRS1985

An inert marker study for palladium silicide formation - Si moves in polycrystalline Pd2Si

A novel use of Ti marker is introduced to investigate the moving species during Pd2Si formation on 111 and 100 line-type Si substrates. Silicide formed from amorphous Si is also studied using a W marker. Although these markers are observed to alter the silicide formation in the initial stage, the moving species can be identified once a normal growth rate is resumed. It is found that Si is the dominant moving species for all three types of Si crystallinity. However, Pd will participate in mass transport when Si motion becomes obstructed.

Ho, K. T.↗

NASA NTRS1985

Palladium silicide formation under the influence of nitrogen and oxygen impurities

The effect of impurities on the growth of the Pd2Si layer upon thermal annealing of a Pd film on 100 line-type and amorphous Si substrates is investigated. Nitrogen and oxygen impurities are introduced into either Pd or Si which are subsequently annealed to form Pd2Si. The complementary techniques of Rutherford backscattering spectrometry, and N-15(p, alpha)C-12 or O-18(p, alpha)N-15 nuclear reaction, are used to investigate the behavior of nitrogen or oxygen and the alterations each creates during silicide formation. Both nitrogen and oxygen retard the silicide growth rate if initially present in Si. When they are initially in Pd, there is no significant retardation; instead, an interesting snow-plowing effect of N or O by the reaction interface of Pd2Si is observed. By using N implanted into Si as a marker, Pd and Si appear to trade roles as the moving species when the silicide front reaches the nitrogen-rich region.

Ho, K. T.↗

NASA NTRS1984

Impurity effects in transition metal silicides

Impurities can affect the properties of silicides directly by virtue of their presence. Impurities can also influence the processes by which silicides are formed. The effect of impurities on the reaction of transition metal films with a silicon substrate induced by thermal annealing are well documented. The interpretation of these results is discussed. It is shown that impurity redistribution is a major factor in determining how significant the effect of an impurity is. Redistribution observed for dopant impurities is also discussed.

Lien, C.-D.↗

NASA NTRS1984

An improved forward I-V method for nonideal Schottky diodes with high series resistance

Two methods are described to obtain the value of the series resistance (R) of a Schottky diode from its forward I-V characteristic. The value of R is then used to plot the curve ln(I) versus V sub D (= V - IR) which becomes a straight line even if ln(I) versus V does not. The ideality factor n and the Schottky-barrier height of the diode then follow from the standard procedure. The main advantages of the methods are: (1) a linear regression can be used to calculate the value of R; (2) many data points are used over the whole data range, which raises the accuracy of the results, and (3) the validity of constant R assumption can be checked by the linearity of the ln (I) versus V sub D curve. The methods are illustrated on the experimental data of a real diode.

Lien, C.-D.↗