Study On Etching Of Antimonides Materials And Electrochemical C-V Technique

The objective of this dissertation includes two aspects: 1. Improving the etching process (wet etching and dry etching) in the antimonides devices fabrication; 2. Measuring the majority carrier concentration profile of antimonides and silicon (with ultra-shallow junction) with an PN4300 semiconductor profile plotter accurately. The related work and results could be summarized as following:1. Two types of etchants consisting of hydrofluoric acid, peroxide and NaKT for the chemical etching of GaSb/AlGaAsSb materials has been studied. These two etchants both have stable etching rate to GaSb and AlGaAsSb materials, under moderate solution composition quite low etching rate could be obtained, which are useful for the fabrication of GaSb/AlGaAsSb devices.2. Reactive ion etching (RIE) characteristics of GaAs, GaSb, InP and InAs using Cl₂/Ar plasma have been investigated, it is that, etching rates and etching profiles as function of etching time, gas flow ratio and RF power. Etch rates of above 0.45μrn/min and 1.2μm/min have been obtained in etching of GaAs and GaSb respectively, while very slow etch rates(<40 nm/min) were observed in etching of In-containing materials, which were linearly increased with the applied RF power. Etched surface have remained smooth over a wide range of plasma conditions in the etching of GaAs, InP and InAs, however, were partly blackened in the etching of GaSb due to a rough appearance.3. Inductively coupled plasma etching of GaSb, AlGaAsSb and InGaAsSb using BCl₃/Ar plasma discharges was investigated for the fabrication of GalnAsSb/AlGaAsSb/GaSb laser diodes. Etching rates and selectivity were characterized as functions of gas flow ratio, accelerating voltage, and ICP source power, and the etching mechanism was discussed in detail. It is observed that the etch rate of GaSb and AlGaAsSb is much higher than that of InGaAsSb. The etched surfaces of GaSb, AlGaAsSb all have comparable root-mean-square (rms) roughness to the unetched samples over a wide range of plasma conditions, however, much rougher in etching of InGaAsSb. The selectivity between GaSb and AlGaAsSb was close to unity over the entire range ofplasma conditions investigated, which is desirable for the fabrication of quaternary antimonide laser diodes.4. A new electrolyte including NaKT, acid or alkali has been developed for accurate EC-V majority carrier concentration profiling of antimonides (GaSb and GaAsSb). By choosing appropriate measuring conditions, good results can be obtained in the profiling of both p-type and n-type GaSb or GaAsSb, which are similar to results measured by Hail method. Commonly used electrolyte (NH4F/HF) for doping profile analysis in Si is employed in the EC-V profiling of ultra-shallow junctions (<50nm) in Si material. Accurate characterization of the carrier concentration can be obtained under appropriate measuring conditions.