CHARACTERIZATION OF INGAASP MATERIALS BY ULTRAHIGH INTENSITY POST-IONIZATION MASS-SPECTROMETRY - RELATIVE SENSITIVITY FACTORS FOR ZINC VERSUS BULK CONSTITUENTS

The first relative sensitivity factors (RSF) for detecting the major a nd dopant elements of optical materials by ultrahigh intensity post-io nization (UHIPI) mass spectrometry are determined. The post-ionization is performed using a single laser wavelength with intensities greater than 10(14) W/cm(2). Zn-implanted InP and In0.4Ga0.1As0.3P0.2 are use d to investigate the photoionization of sputtered atoms and molecules. Under optimal conditions, the UHIPI RSF's for atomic singly charged I n, Ga, and Zn are nearly equal; that is, the ratio of UHIPI signals is equal to the concentration ratio. In principle, no standards are need ed for quantitative analysis. Arsenic and P, with higher ionization po tentials, are not detected as efficiently as other elements. The detec ted mass balance is usually group III rich. An entire mass spectrum is necessary for complete characterization of all elements and adjustmen t of their RSF's because many sputtered molecules are detected contain ing the group V elements. Multiply charged species compose about 10% o f the detected ions.