Native oxidation of aluminum-bearing III-V semiconductors with applications to edge- and surface-emitting lasers and to the stabilization of light emitting diodes

In this work, a water vapor oxidation process is used to convert high Al composition $\rm Al\sb{x}Ga\sb{1-x}As$ to a stable native oxide. The native oxides described are formed at temperatures in the range of 400$\rm\sp\circ C$ to 500$\rm\sp\circ C.$ Some of the basic properties of the native oxide are described. These properties include the insulating and diffusion masking nature of the oxide as well as the anisotropic behavior of the oxidation process.The high quality native oxide is then applied to laser devices in the $\rm Al\sb{x}Ga\sb{1-x}$As-GaAs and $\rm Al\sb{y}Ga\sb{1 -y}$As-GaAs-In$\rm\sb{x}Ga\sb{1-x}As$ material systems and to the stabilization of $\rm Al\sb{y}Ga\sb{1-y}As$-$\rm In\sb{0.5}(Al\sb{x}Ga\sb{1-x})\sb{0.5}P$ light emitting diodes. Data are presented on a high-performance native-oxide coupled-stripe $\rm Al\sb{y}Ga\sb{1-y}As$-GaAs-In$\rm\sb{x}Ga\sb{1-x}As$ quantum well heterostructure laser array realized by the "wet" oxidation of the upper $\rm Al\sb{y}Ga\sb{1-y}As$ confining layer for current definition. Also, data are presented on the (300 K and 77 K) continuous photopumped laser operation of oxide-embedded $\rm Al\sb{y}Ga\sb{1-y}As$-GaAs-In$\rm\sb{x}Ga\sb{1-x}As$ quantum-well heterostructures. The active region is sandwiched within native-oxide-semiconductor stacks. The native-oxide layers are formed after crystal growth by selectively oxidizing along high Al-composition heterolayers. The active region is shown to remain intact without any significant degradation in laser performance. The oxide-embedded laser structure is optimized for vertical-cavity laser operation utilizing large-index-step high-contrast distributed Bragg reflector mirrors formed by the selective lateral oxidation process. Edge- and vertical-cavity photopumped operations of devices with short period upper and lower mirrors are demonstrated. The vertical-cavity lasers also exhibit "hot"-carrier recombination.Finally, data are presented on the electrical behavior and the reliabillty of post-fabrication native-oxide-passivated visible-spectrum AlGaAs-In(AlGa)P p-n heterostructure light emitting diodes (LEDs). The LEDs are oxidized after metallization, thus sealing all of the exposed AlGaAs crystal at cracks, fissures, and edges against atmospheric hydrolysis without degrading their light-output characteristics. The current-voltage (I-V) characteristics of the oxide-passivated LEDs are shown to exhibit normal p-n diode behavior. Above all, the reliability of the oxidized devices in high-humidity conditions is greatly improved compared to those of otherwise identical unoxidized LEDs.U of I OnlyETDs are only available to UIUC Users without author permissio