Electron irradiation-induced increase of minority carrier diffusion length, mobility, and lifetime in Mg-doped AlN∕AlGaN short period superlattice

Abstract

Minority carrier diffusion length in a p-type Mg-doped AlN∕Al0.08Ga0.92N short period superlattice was shown to undergo a multifold and persistent (for at least 1week) increase under continuous irradiation by low-energy beam of a scanning electron microscope. Since neither the diffusion length itself nor the rate of its increase exhibited any measurable temperature dependence, it is concluded that this phenomenon is attributable to the increase in mobility of minority electrons in the two-dimensional electron gas, which in turn is limited by defect scattering. Cathodoluminescence spectroscopy revealed ∼40% growth of carrier lifetime under irradiation with an activation energy of 240meV.

III-Nitride Short Period Superlattices for Deep UV Light Emitters

“…It is clearly seen that the hole concentration varies very little with the temperature in SPSLs, and is highly dependent on the temperature (almost 1.5 orders of magnitude) in a uniformly Mg-doped Al 0.05 Ga 0.95 N layer. Similar experimental results were reported by many different teams [45,[105][106][107][108][109][110][111][112][113][114][115].…”

“…The concentration of holes can be at the level of 10 18 cm −3 , even in SPSLs with high average AlN content, as is seen in Figure 6a. Such structures were obtained using both MBE and MOCVD methods [25,41,42,45,91,[105][106][107][108][109][110]. Figure 6b shows the results of temperature-dependent Hall characterization of three SPSLs and one AlGaN layer.…”

Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

“…Application of Mg-doped AlN/(AlGaN SPSLs) grown by MBE [ 60 , 83 , 84 , 85 , 86 , 87 , 88 ] and MOVPE [ 89 , 90 , 91 , 92 ] is a solution which enables (i) obtaining comparably high concentrations of holes averaged over the superlattice period (see Figure 5 b, where asterisks correspond to the data obtained by SPSLs) and (ii) significantly reducing the acceptor activation energy. For example, in MBE-grown AlN/Al x Ga 1− x N (0.03 < x < 0.08) SPSLs with 0.5–0.8 nm wells and 1.5–2 nm periods, the average AlN concentration could be changed in the range of y av = 0.5–0.8 [ 81 , 88 ] by variation of the well-to-period width ratio.…”

“…Therefore, to achieve a uniform carrier injection in the active region of UVC LDs with an acceptable optical confinement factor, a prospective solution is to substitute the conventional SQWs and DQWs with undoped GaN/AlGaN or AlGaN/AlN SPSLs with a high effective Al content. This approach has been successfully used in DUV-LEDs with SPSL active regions ~25–40 nm wide [ 86 ]. Since the SPSL active regions can be realized with thicknesses up to hundreds of nanometers, this would also result in remarkably higher optical confinement factors.…”

Silicon ultrafast recovery diode with leakage current reduced via the combined lifetime process of gold diffusion and electron-beam irradiation

“…However, this method significantly increases the leakage current [18]. In contrast, there is another method to control the lifetime of minority carriers by forming defects via electron-beam or particle ion-beam irradiation [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37], and the physical and electrical characteristics of the defects have been investigated [38][39][40][41][42][43][44][45][46]. The leakage current can be reduced to less than that of a solely Au-diffused diode by generating defects via electron-beam irradiation (EI) [47].…”