Compensation ratio-dependent concentration of a VInH4 complex in n-type liquid encapsulated Czochralski InP

The concentration of hydroen-indium vacancy complex VInH4 in liquid encapsulated Czochralski undoped and Fe-doped n-type InP has been studied by low-temperature infrared absorption spectroscopy. The VInH4 complex is found to be a dominant intrinsic shallow donor defect with concentrations up to similar to 10(16) cm(-3) in as-grown liquid encapsulated Czochralski InP. The concentration of the VInH4 complex is found to increase with the compensation ratio in good agreement with the proposed defect formation model of Walukiewicz [W. Walukiewicz, Phys. Rev. B 37, 4760 (1998); Appl. Phys. Lett. 54, 2094 (1989)], which predicts a Fermi-level-dependent concentration of amphoteric defects. (C) 1998 American Institute of Physics, [S0003-6951(98)04435-0].

A fast-settling frequency-presetting PLL frequency synthesizer with process variation compensation and spur reduction

This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is -108 dBc/Hz@1MHz.The reference spur is -52 dBc.

Improved optical photoluminescence by charge compensation in the phosphor system CaMoO4: Eu3+

It has been found that charge compensated CaMoO4:Eu3+ phosphors show greatly enhanced red emission under 393 and 467 nm-excitation, compared with CaMoO4:Eu3+ without charge compensation. Two approaches to charge compensation, (a) 2Ca(2+) -> EU3+ + M+, where M+ is a monovalent cation like Li+, Na+ and K+ acting as a charge compensator; (b) 3Ca(2+) -> 2EU(3+) + vacancy, are investigated. The influence of sintering temperature and Eu3+ concentration on the luminescent property of phosphor samples is also discussed.

CHARGE COMPENSATION AND VALENCY STABILITY OF EU(II)-DOPED KMGF3 CRYSTAL

The spectrochemistry of Eu2+-doped perovskite KMgF3 was examined and discussed. Eu2+ can replace some of the K+ in the KMgF3 crystal, and simultaneously the corresponding cation hole can be compensated with the F- or O2- in the matrix. The emission intensity of Eu2+ due to the f --> f transition increased when Na+, Rb+ or F- was doped in KMgF3:Eu2+. Two mechanisms of charge compensation were proposed. No obvious valence change of Eu2+ occurred in KMgF3:Eu2+ after calcinating at high temperature, e.g. 900-degrees-C. It was found that the valence stability of Eu2+ improved after incorporation into the matrix.