Angle lapping

Diffusivities of various elements ate determined experimentally. Dopant profiles can be determined. The junction depth can be measured by chemically staining an angle-lapped sample with an HE/HNO mixture. The -type region of the junction stains darker than the n-ty e region. The sheet resistivity can also be measured using a four-point probe measurement. These two techniques ate used for process monitoring. 

Fig. 18. Angle-lapped section of n-type Si that has been boron-implanted and then partly hydrogenated to form a 0.23 /u.m-thick layer of n-type, H-neutralized material. The n-type regions are preferentially stained.

Structui High depth resolution ( lOOA) angle lapping is... 

Figure 11 contains an SEM photo of a stained angle-lapped section from a 50-layer InAsP/InP multilayer structure — each with a 200 X thickness. 

Ball cratering is related to angle lapping,in which the sample is polished at a slight bevel. Similar measurements can also be made on the wall of a sputter crater, but without an easy conversion from a lateral distance to depth. Although these methods are destructive, they have the advantage over ion bombardment that the measurement along the crater wall can be repeated. 

The real shape of the p-n-junction can be revealed by angle lapping and etching techniques /34/. These investigations are essential for the control of the grain size of the CdS films and the thickness and grain boundary penetration of the CUj S. 

Fig. 8. The dependence on contact angle of the magnitude and location of maximum stress concentration in a lap shear test. As the contact angle decreases, the stress concentration decreases, and its locus moves toward the center-plane of the adhesive phase. Redrawn from ref. [51].

In peel separation, the adhesive simply peels away from the surface. Lap shear occurs when the adhered material is subjected to a force that is applied parallel to the bonding plane. Here, the bond becomes deformed and stretched after initial rupture of some portion of the bond. It is a sliding type of failure. In tensile detachment, bond disruption occurs as force is applied at right angles to the bonding surface. Tensile detachment is a ripping type of bond disruption. 

The rate of peel loading is more important than in lap shear loading, and it should be known and controlled as closely as possible. The rate at which the load is applied is usually specified in the ASTM test procedure. Adhesive thickness also has a significant effect on peel strength values, as does the angle of peeling. 

In contrast with the co-cured single lap joint, tensile load bearing capacity of the co-cured double lap joint decreases as the stacking angle of the composite adherend increases. Sint e the co-cured double lap joint has symmetrical configuration, it is important to consider the out-ofplane shear stress rather than the out-of-plane peel stress in designing the joint. 

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