Resonance ionization mass spectrometry of AI(x)Ga(1-x)As: depth resolution, sensitivity, and matrix effects.
Resonance ionization mass spectrometry (RIMS) of neutral atoms sputtered from III-V compound semiconductors such as Al(x)Ga(1-x)As provides information that is complementary to secondary ion mass spectrometry with the added advantages of rejecting mass interferences, retaining good sensitivity, and reducing matrix effects. A GaAs sample, delta doped with Be, is used to measure depth resolution and Be secondary ion and atom yield. Because of the coupling of the pulsed RIMS lasers and continuous sputtering beam, duty cycle factors are used to determine the atom yield. A 3-D model of the geometrical overlap of laser and sputtered atoms is developed to ascertain the same utilization efficiency in RIMS. About 30% of the atoms sputtered in 1 micros are calculated to be in the laser beam. The atom yield was found to be near unity. The time-gated RIMS useful yield is ~2%. RIMS is used to minimize matrix effects in a depth profile of a Be-implanted AlAs/A1(0.2)Ga(0.8)As heterostructure and shows that Be diffuses from higher Al-containing layers at concentrations near 10(19) cm(-3). The atomization of As is shown to be affected by the Al content in a GaAs/Al(0.5)Ga(0.5)As structure.
Downey
S W
SW
Kopf
R F
RF
Schubert
E F
EF
Kuo
J M
JM