Studies Of Dry Etching And Ions Implantation On The Luminescence Property Of Ⅲ-Ⅴ Group Semiconductor Quantum Wells

Dry etching and ions implantation are two basic processes that have been widely used in the fabrication of semiconductor photoelectronic devices. Although dry etching and ions implantation show many advantages, they may introduce damage to the processed semiconductor materials and devices, and deteriorate optical and electrical properties of the materials and devices. Therefore, how to avoid or minish the device damage during fabrication processes is worthy of studying. To resolve this scientific problem, following research work was done in the thesis:1. The physical parameters used in low energy dry etching process are calculated which includes defects creation rate, defects distribution on etching surface, etching damage depth, and the electrical conductance of epitaxial layers. It can be concluded as that: (1) The defect density under the etching surface that is created by dry etching decreases exponentially with the increase of depth, but it increases with the prolongation of etching time and turns to be saturated eventually; (2) The damage depth increases firstly with the etching depth and then turns to a constant value when the defect depletion rate equals to the defect creation rate. At a same etching depth, the deeper of the tunnelling depth under the etching surface, the bigger of the damage depth.2. Special structures of III-V group semiconductor quantum wells (QWs) used in the study of dry etching damage mechanism and ions implantation experiments are designed. The structures such as InAsP/InP,InAsP/InGaAsP QWs are grown using Gas Source Molecular Beam Epitaxy (GSMBE) and the InGaN/AlGaN strained multiple quantum wells (SMQWs) are grown using Metal Organic Chemical Vapor Deposition (MOCVD).3. The luminescence properties of the QWs affected by dry etching and ions implantation are studied. The cap layer of the QWs strutctures is etched different depths by Inductively Coupled Plasma (ICP) and the PL intensities of QWs are found to increase firstly and then decrease with the enlargement of etching depth. When the ICP etching depth is 45 nm, the PL intensity of InAsP/InP SMQWs is enhanced about 5～7 times. When the cap layer of InGaN/AlGaN SMQWs is etched 95 nm by ICP, the PL intensity of QWs is enhanced about 3 times. The mechanism of the PL intensity enhancement phenomena is attributed to that: (1) The tunnelling of Ar⁺ during the etching process introduces new radiative recombination centers inside the QWs structure; (2) The roughness of the dry etched surface is also contributed to the enhancement of PL intensities.The relation between etching depth and damage depth is determined and the etching damage is about 40 nm when the cap layer of InAsP/InP SMQWs is etched 75 nm. With the enlargement of etching depth, High-density Ar⁺ ions tunnelled into the QWs form non-radiative recombination centers that lead to the decrease of the QWs PL intensity.It is found that PL intensities of InAsP/InP SMQWs can also be enhanced by implanting H⁺ into the QWs because the tunnelling of H⁺ can anneal the intrinsic defects inside the QWs structure. The PL intensity of the InAsP/InP SMQWs is enhanced about 1.5 times when the implantation energy and dose of H⁺ are 25 KeV and 10¹⁰/cm², respectively.4. The relation between temperature and the QW band gap, exciton binding energy are calculated theoretically. The dependence of luminescence properties of the ICP etched InAsP/InP and InAsP/InGaAsP SMQWs on temperature is studied. Following experimental phenomena are founded: (1) The PL intensity enhancement factor of the QWs increases with the rise of temperature; (2) The position movement of In or P, the inhomogeneity caused by defects and strain may lead to the potential fluctuation inside the QWs structure. The interaction between the carriers and the fluctuant potential produces band tail states in the exciton state density and the recombination of excitons at the band tail states lead to the red shift of the PL position of the dry etched QWs; (3) The defects and the atom position change inside the QWs structures make the full width at the half maximum of PL spectra bigger than that of the as grown sample.5. The intermixing of InAsP/InP SMQWs is realized by the ICP etching and followed by fast annealing at high temperature. Also, the intermixing of InAsP/InP SMQWs is realized through implantation of H⁺ and P⁺ separately into the QWs followed the fast annealing at high temperature. At a low temperature (10 K), when the ICP etching depth is 180 nm, the PL positions of InAsP/InP strained double QWs blue-shift about 39 nm. When the H⁺ implantation energy is 25 KeV, implantation dose is 10¹⁴/cm², the PL positions of InAsP/InGaAsP SMQWs blue-shift about 33 nm. When the P⁺ implantation energy is 25 KeV, implantation dose is 1×10¹³/cm², the PL positions of InAsP/InGaAsP SMQWs blue-shift about 37 nm.The above results are beneficial to the guidance of the dry etching and ions implantation of III-V group of semiconductor materials and devices.